Changes in Activeview are not in exported image

I am trying to export without Arcmap so i created a webservice in C#. The export works OK. The problem is that whatever i do with the activeview(pan, zoom) it is not affected to the exported image. I always get the same image. So the ZoomInCenter() doesn't work. Please help. (Using Arcgis 9.3.1 and visual studio 2008)

public void ZoomInCenter()
{ 
    IMapDocument ipMapDoc;
    ipMapDoc = new MapDocumentClass();
    ipMapDoc.Open(@"c:\temp\tryout.mxt", "");
    IActiveView activeView = ipMapDoc.PageLayout as IActiveView;
    activeView.Activate(GetDesktopWindow());
    IEnvelope envelope = activeView.Extent;

    // Get the center point of the envelope.
    IPoint centerPoint = new PointClass();
    centerPoint.X = ((envelope.XMax - envelope.XMin) / 2) + envelope.XMin;
    centerPoint.Y = ((envelope.YMax - envelope.YMin) / 2) + envelope.YMin;

    //Resize the envelope width.
    envelope.Width = envelope.Width / 2;

    //Resize the envelope height.
    envelope.Height = envelope.Height / 2;

    //Move the envelope to the center point.
    envelope.CenterAt(centerPoint);

    //Set the envelope to view extent.
    activeView.Extent = envelope;
    activeView.Refresh();
    CreateJPEGFromActiveView(activeView, @"c:\temp\New.jpg");
}      
 public System.Boolean CreateJPEGFromActiveView(ESRI.ArcGIS.Carto.IActiveView activeView, System.String pathFileName)
{
    //parameter check
    if (activeView == null || !(pathFileName.EndsWith(".jpg")))
    {
        return false;
    }
    ESRI.ArcGIS.Output.IExport export = new ESRI.ArcGIS.Output.ExportJPEGClass();
    export.ExportFileName = pathFileName;

    // Microsoft Windows default DPI resolution
    export.Resolution = 96;
    ESRI.ArcGIS.Display.tagRECT exportRECT = activeView.ExportFrame;
    ESRI.ArcGIS.Geometry.IEnvelope envelope = new ESRI.ArcGIS.Geometry.EnvelopeClass();
    envelope.PutCoords(exportRECT.left, exportRECT.top, exportRECT.right, exportRECT.bottom);
    export.PixelBounds = envelope;
    System.Int32 hDC = export.StartExporting();
    activeView.Output(hDC, (System.Int16)export.Resolution, ref exportRECT, null, null);

    // Finish writing the export file and cleanup any intermediate files
    export.FinishExporting();
    export.Cleanup();

    return true;
}