DOCUMENT:Q190460  07-AUG-1998  [vbwin]
TITLE   :BUG: Type Mismatch Error in Client After Modifying Server DLL
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:
OPER/SYS:WINDOWS
KEYWORDS:

======================================================================
---------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Visual Basic Learning, Professional, and Enterprise Editions
   for Windows, version 6.0
---------------------------------------------------------------------

SYMPTOMS
========

If an ActiveX DLL server has two classes and one class implements the
other, running a compiled client project referencing the server will
generate the following error after modifying and recompiling the server
with binary compatibility:

   Run-time error 13: Type mismatch

RESOLUTION
==========

Reopen the client project and compile it again.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed
at the beginning of this article. We are researching this bug and will post
new information here in the Microsoft Knowledge Base as it becomes
available.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

Create the Server
-----------------

1. Start a new ActiveX DLL project in Visual Basic. Class1 is created by
   default.

2. Select Project1 Properties from the Project menu and change the Project
   Name to "Server."

3. Select Add Class Module from the Project menu to add Class2 to the
   project.

4. Paste the following code in Class2:

      Public Sub Test()
      End Sub

5. Paste the following code in Class1:

      Implements Class2

      Private Sub Class2_Test()
         MsgBox "Testing the Server"
      End Sub

6. Select Make Server.dll from the File menu to compile the project.

7. Save the Server project files.

Create the Client
-----------------

1. Start a new Standard EXE project in Visual Basic 6.0. Form1 is created
   by default.

2. Select Project1 Properties from the Project menu, and change the Project
   Name to "Client."

3. Select References from the Project menu, and select "Server."

4. Paste the following code in Form1's code module:

      Private Sub Form_Load()
         Dim x As Server.Class2
         Set x = New Server.Class1
         TestMethod x
      End Sub

      Private Sub TestMethod (x As Server.Class2)
         x.Test
      End Sub

5. Select Make Client.exe from the File menu.

Test the Client with the Server
-------------------------------

1. Run Client.exe outside the Visual Basic design environment. The program
   runs correctly.

2. Reopen the Server.dll project and add the following code to Class2:

      Public Sub Test2()
      End Sub

3. Add the following code to Class1:

      Private Sub Class2_Test2()
      End Sub

4. Select Server Properties from the Project menu, and select the Binary
   Compatibility option on the Component tab.

5. Select Make Server.dll from the File menu to compile the project.
   Overwrite the existing Server.dll.

6. Run Client.exe again. Note that the following error occurs:

      Run-time error 13: Type mismatch

Additional query words: kbdss kbDSupport kbVBp kbVBp600bug kbCompiler
======================================================================
Platform          : WINDOWS
Issue type        : kbbug

=============================================================================

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Copyright Microsoft Corporation 1998.