首先捕获异常并找出异常的消息是什么。那应该（希望）给你一个线索。

Start by catching the exception and finding out what the exception's message is. That should (hopefully) give you a clue.

         try
         {
             // Your code that generates the exception goes here.
         }
         catch (System.Exception ex)
         {
            // Display or log ex.Message here, 
            // or check it out in the debugger.
         }