In a Microsoft .NET Framework application, when you perform a late bind to call a Component Object Model (COM) component that returns a structure, you may receive the following exception when you run the application:

To work around this bug, perform an early bind instead of a late bind while you call the COM component.

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

Steps to Reproduce the Behavior

To create a COM DLL, follow these steps:

1. In Microsoft Visual Basic 6.0, create a new Microsoft ActiveX DLL project.
2. Copy the following code in the Class1 class:

   ' Custom structure
   Public Type struct1
      x As Integer
   End Type
   
   ' Public function returning structure
   Public Function test() As struct1
   End Function

3. On the File menu, click Make Project1.dll.

To call a COM component, follow these steps:

1. Open Microsoft Visual Studio .NET.
2. On the File menu, point to New, and then click Project.
3. Under Project Types, click to select Visual Basic Projects or Visual C# Projects.
4. Under Templates, click to select Console Application. Click OK.
5. In Solution Explorer, right-click Reference, and then click Add Reference.
6. On the COM Properties page, click Browse.
7. Locate the new Project1.dll file, and then click Open. Click OK.
8. Copy the following code in the Main method.
   
   Visual Basic .NET Code

   Dim o As Object = New Project1.Class1()
   Dim s As Project1.struct1
   
   'Calling function 'test' through latebound
   s = o.test
   

   Visual C# .NET Code

   Type objClassType;
   
   objClassType = Type.GetTypeFromProgID("Project1.Class1");
   object myObj;
   
   myObj = Activator.CreateInstance(objClassType);
   objClassType.InvokeMember("test",System.Reflection.BindingFlags.InvokeMethod ,null,myObj,null);
   

9. On the Debug menu, click Start to run the application.
   
   You may receive the exception in the "Symptoms" section of this article.

For more information about COM Interop, visit the following MSDN Web site:

COM Interop
http://msdn2.microsoft.com/en-us/library/6bw51z5z(vs.71).aspx (http://msdn2.microsoft.com/en-us/library/6bw51z5z(vs.71).aspx)