Change what you have to:
AcadApp = Autodesk.AutoCAD.ApplicationServices.Application
This gives the Managed AutoCAD application object.
The reason it is failing your way is that you are trying to use COM to return an AutoCAD object, but that object is not fully initialized when you try to acquire it, resulting in a COM exception (time out) 'Failed to (create/acquire) object" or something like that.
If you need the COM AutoCAD application object, then use this :
AcadApp = (Autodesk.AutoCAD.Interop.AcadApplication) Autodesk.AutoCAD.ApplicationServices.Application.AcadApplication