ASP.NET not injecting javascript function

Any idea why my function isn't getting injected into the web page? I'm pretty sure I've done this before and it worked, but when I launch from VS and look at the page I don't see it anywhere.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string deviceID = Guid.NewGuid().ToString();
        string deviceFunction = "function GetDeviceID() { return '" + deviceID + "'; }";

        ClientScript.RegisterClientScriptBlock(GetType(), "DeviceID", deviceFunction, true);

    }
}