Inconsistent Behavior With Commands on Menu vs. Toolbar

Question

I have added a new command by implementing a package. I want this command to appear on the "Build" menu, and in the "Build" toolbar, but only when the project factory for my new project type has context. I am able to do this succesfully on the "Build" menu, but my new command is only greyed out, not absent from the "Build" toolbar, when it should be. My .ctc file looks as follows:

CMDS_SECTION guidBuildToolbarsPkg

  MENUS_BEGIN
    // NewMenu                              Relative to Group                       Priority    Type        Name                    Text
  MENUS_END

  NEWGROUPS_BEGIN
    // NewGroup                              Parent Group                            Priority
    guidBuildToolbarsCmdSet:MyBuildGroup,    guidSHLMainMenu:IDM_VS_MENU_BUILD,    0x0600;
NEWGROUPS_END

  BUTTONS_BEGIN
    // Command                    Parent Group                Priority    Image            Type    Visibility       
    guidBuildToolbarsCmdSet:cmdidDriver, guidBuildToolbarsCmdSet:MyBuildGroup, 0x0100, guidBuildToolbarsCmdSet:bmpPic1, BUTTON, DEFAULTINVISIBLE | DYNAMICVISIBILITY, "Driver";
  BUTTONS_END

  BITMAPS_BEGIN
    guidBuildToolbarsCmdSet:IDB_MENU_IMAGES,    bmpPic1, bmpPic2, bmpPicSmile, bmpPicX, bmpPicArrows;
  BITMAPS_END

CMDS_END

CMDUSED_SECTION
CMDUSED_END

CMDPLACEMENT_SECTION
  // Command                             Group                                Priority
  guidBuildToolbarsCmdSet:cmdidDriver,    guidSHLMainMenu:IDG_VS_BUILDBAR,        0x0000;
CMDPLACEMENT_END

VISIBILITY_SECTION
    // Command                          GUID when visible
  guidBuildToolbarsCmdSet:cmdidDriver, guidDesignProjecType;
VISIBILITY_END
 
It seems that since I defined the button for cmdidDriver to be DEFAULTINVISIBLE | DYNAMICVISIBILITY, and I have set up my VISIBILITY_SECTION as I need, that the two instances of the "Driver" button should behave the same, but they don't. Any pointers?

Thanks,

-Ian