控制台程序直接打开mxd放大缩小后获取不到当前比例尺了？

mapdoc = new MapDocumentClass(); 

mapdoc.Open(@G:\Untitled.mxd); 

actView = mapdoc.ActiveView; 

//激活 

actView.Activate(GetDesktopWindow()); 



IEnvelope currentEnv = actView.Extent; 

currentEnv.Expand(1.2, 1.2, true); 

actView.Extent = currentEnv; 

actView.Refresh(); 



double newscale = actView.FocusMap.MapScale; 

MessageBox.Show(newscale.ToString()); 

} 



[System.Runtime.InteropServices.DllImport(user32.dll)] 



public extern static int GetDesktopWindow();