PRB: Component Gallery Unable to Import OLE Control

• Microsoft Visual C++, 32-bit Edition, versions 4.0, 4.1

SYMPTOMS

Microsoft Developer Studio reports the error message:

   Unable to import OLE control.

CAUSE

By default, MFC applications use ID binding to call methods in ActiveX controls. Because of this behavior, Developer Studio checks to make sure that the version of the type library is the same as that of the control. If the versions are not the same, Developer Studio reports an error.

This error is usually caused by incrementing the version of the ActiveX Control but not the version of the type library.

For more information on ID binding, please see the following article in the Microsoft Knowledge Base:

   ARTICLE ID: Q138138
   TITLE     : Three Binding Types (Late, ID, Early) Possible in VB for
               Apps

RESOLUTION

Make sure that the version of the ActiveX control matches the version of its type library.

In an MFC control, the version of the control is represented by constants found in the implementation file for the OLE control class:

   const WORD _wVerMajor = 1;
   const WORD _wVerMinor = 0;

   [ uuid(AFCDB500-BB23-11CF-A685-00AA00A70FC2), version(1.0),
     helpstring("VersionTest OLE Control module"), control ]

STATUS

This behavior is by design.

MORE INFORMATION

An updated version of this control would have version identifiers similar to the following:

   const WORD _wVerMajor = 2;
   const WORD _wVerMinor = 4;

   [ uuid(AFCDB500-BB23-11CF-A685-00AA00A70FC2), version(2.4),
     helpstring("VersionTest OLE Control module"), control ]