You may receive a "There is no object in this control" error message when you open a form that was saved in Access 97 and that contains ActiveX controls developed with ATL

RESOLUTION

If you are developing a control using ATL and plan to use it in Microsoft Access, be sure to support the Enabled stock property. The ATL COM Object Wizard can add the needed code if you select Enabled from the list of available stock properties on the last property page when inserting the full control.

If you already have a control project that does not have the Enabled stock property selected, you can add support for it using the steps outlined here.

1. Determine whether or not your control has support for ANY stock properties. If not, modify the header file for the control to include support for ATL's default stock property support and comment out the IDispatchImpl derived class. For example:

   class ATL_NO_VTABLE CATLAccessKBControl :
     public CComObjectRootEx<CComSingleThreadModel>,
   //public IDispatchImpl<IATLAccessKBControl, &IID_IATLAccessKBControl,
   \    //&LIBID_ATLACCESSCONTROLLib>,
   public CStockPropImpl<CATLAccessKBControl, IATLAccessKBControl, \ 
             &IID_IATLAccessKBControl, &LIBID_ATLACCESSCONTROLLib>,
   //rest of interfaces that are derived....
   					

2. Modify the IDL file by adding support for propget/propput methods for DISPID_ENABLED. For example:

   [
     object,
     uuid(91A905D0-8B9F-11D2-8F10-00C04F94089E),
     dual,
     pointer_default(unique)
   ]
   interface IATLAccessKBControl : IDispatch
   {
   [propput, id(DISPID_ENABLED)] HRESULT Enabled([in]VARIANT_BOOL
      vbool);
   [propget, id(DISPID_ENABLED)] HRESULT Enabled([out,retval] \ 
      VARIANT_BOOL*pbool);
   };
   					

3. Add a member variable to the control's header file, which will have the enabled stock property value. For example:

   class ATL_NO_VTABLE CATLAccessKBControl :
     public CComObjectRootEx<CComSingleThreadModel>,
   //rest of interfaces that are derived...
   {
     public:
       BOOL m_bEnabled;
     //rest of class definition
   };
   					

   Be sure to name the property "m_bEnabled" so ATL framework correctly sets it.