android eclipse error binary xml file error inflating class android.widget.relativelayout

im new in android i made an app for sniffing wifi access points and i have the following errors in logcat my manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.weedow2"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
  android:minSdkVersion="8"
  android:targetSdkVersion="19" />

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />

<application
  android:allowBackup="true"
  android:icon="@drawable/ic_launcher"
  android:label="@string/app_name"
  android:theme="@style/AppTheme" >
  <activity
     android:name=".MainActivity"
     android:label="@string/app_name" >
     <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
     </intent-filter>
  </activity>
      <activity
     android:name=".ListWifiActivity"
     android:label="@string/app_name" >
  </activity>
</application>
</manifest>

MainActivity.java

package com.example.weedow2;

import java.util.List;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.wifi.ScanResult;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;


public class MainActivity extends Activity {

WifiManager mainWifiObj;
WifiScanReceiver wifiReciever;
ListView list;
String wifis[];
public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  list = (ListView)findViewById(R.id.listView1);
  mainWifiObj = (WifiManager) getSystemService(Context.WIFI_SERVICE);
  wifiReciever = new WifiScanReceiver();
  mainWifiObj.startScan();
}


protected void onPause() {
  unregisterReceiver(wifiReciever);
  super.onPause();
}

protected void onResume() {
  registerReceiver(wifiReciever, new IntentFilter(
  WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
  super.onResume();
}

class WifiScanReceiver extends BroadcastReceiver {
  @SuppressLint("UseValueOf")
  public void onReceive(Context c, Intent intent) {
     List<ScanResult> wifiScanList = mainWifiObj.getScanResults();
     wifis = new String[wifiScanList.size()];
     for(int i = 0; i < wifiScanList.size(); i++){
        wifis[i] = ((wifiScanList.get(i)).toString());
     }

     list.setAdapter(new ArrayAdapter<String>(getApplicationContext(),
     android.R.layout.simple_list_item_1,wifis));
  }
}

}

and activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:paddingBottom="@+id/activity_vertical_margin"
 android:paddingLeft="@+id/activity_horizontal_margin"
 android:paddingRight="@+id/activity_horizontal_margin"
 android:paddingTop="@+id/activity_vertical_margin"
 tools:context=".MainActivity" >

<ListView
  android:id="@+id/listView1"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:layout_alignParentTop="true"
  android:layout_centerHorizontal="true"
  android:drawSelectorOnTop="false"
  android:background="@android:color/background_dark"
  android:listSelector="@android:color/darker_gray" >

</ListView>
</RelativeLayout>

and i have the following error

10-23 12:02:07.064: E/AndroidRuntime(277): FATAL EXCEPTION: main 10-23 12:02:07.064: E/AndroidRuntime(277): java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.example.weedow2/com.example.weedow2.MainActivity}: android.view.InflateException: Binary XML file line #1: Error inflating class android.widget.RelativeLayout 10-23 12:02:07.064: E/AndroidRuntime(277): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.os.Handler.dispatchMessage(Handler.java:99) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.os.Looper.loop(Looper.java:123) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.app.ActivityThread.main(ActivityThread.java:4627) 10-23 12:02:07.064: E/AndroidRuntime(277): at java.lang.reflect.Method.invokeNative(Native Method) 10-23 12:02:07.064: E/AndroidRuntime(277): at java.lang.reflect.Method.invoke(Method.java:521) 10-23 12:02:07.064: E/AndroidRuntime(277): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 10-23 12:02:07.064: E/AndroidRuntime(277): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 10-23 12:02:07.064: E/AndroidRuntime(277): at dalvik.system.NativeStart.main(Native Method) 10-23 12:02:07.064: E/AndroidRuntime(277): Caused by: android.view.InflateException: Binary XML file line #1: Error inflating class android.widget.RelativeLayout 10-23 12:02:07.064: E/AndroidRuntime(277): at android.view.LayoutInflater.createView(LayoutInflater.java:513) 10-23 12:02:07.064: E/AndroidRuntime(277): at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:563) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.view.LayoutInflater.inflate(LayoutInflater.java:385) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.view.LayoutInflater.inflate(LayoutInflater.java:320) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.view.LayoutInflater.inflate(LayoutInflater.java:276) 10-23 12:02:07.064: E/AndroidRuntime(277): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:198) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.app.Activity.setContentView(Activity.java:1647) 10-23 12:02:07.064: E/AndroidRuntime(277): at com.example.weedow2.MainActivity.onCreate(MainActivity.java:27) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 10-23 12:02:07.064: E/AndroidRuntime(277): ... 11 more 10-23 12:02:07.064: E/AndroidRuntime(277): Caused by: java.lang.reflect.InvocationTargetException 10-23 12:02:07.064: E/AndroidRuntime(277): at android.widget.RelativeLayout.(RelativeLayout.java:170) 10-23 12:02:07.064: E/AndroidRuntime(277): at java.lang.reflect.Constructor.constructNative(Native Method) 10-23 12:02:07.064: E/AndroidRuntime(277): at java.lang.reflect.Constructor.newInstance(Constructor.java:446) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.view.LayoutInflater.createView(LayoutInflater.java:500) 10-23 12:02:07.064: E/AndroidRuntime(277): ... 21 more 10-23 12:02:07.064: E/AndroidRuntime(277): Caused by: java.lang.UnsupportedOperationException: Can't convert to dimension: type=0x12 10-23 12:02:07.064: E/AndroidRuntime(277): at android.content.res.TypedArray.getDimensionPixelSize(TypedArray.java:463) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.view.View.(View.java:1891) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.view.View.(View.java:1834) 10-23 12:02:07.064: E/AndroidRuntime(277): at android.view.ViewGroup.(ViewGroup.java:285) 10-23 12:02:07.064: E/AndroidRuntime(277): ... 25 more

but this line:

Unable to start activity ComponentInfo{com.example.weedow2/com.example.weedow2.MainActivity}:android.view.InflateException: Binary XML file line #1: Error inflating class android.widget.RelativeLayout

is important