在其周围放置一个try/catch块，并在调试器下运行代码，您将确切地了解到什么.是错误的.

Put a try/catch block around it and run the code under the debugger, and you''ll find out exactly what''s wrong.

您的应用程序中是否确实存在AddForm，请检查此代码并查找错误

Is that AddForm really exist in your application, Check this code and find what the error is

Type tp=Type.GetType(formname, true);

这是用于获取类型的语法

This are the syntaxes used to get type

Type GetType(string typeName);

   Type GetType(string typeName, bool throwOnError);

   Type GetType(string typeName, bool throwOnError, bool ignoreCase);