Disable Popup Menu in Control Button

I want to ask, how do I disable pop-up menu on the control button. For more details, like the following picture.

please help ---
thank's

samples in the folder just using syntax like this:
    Set ControlSelect = GroupFind.Add(xtpControlPopup, ID_EDIT_SELECT, "&Select")
        ControlSelect.CommandBar.Controls.Add xtpControlButton, ID_EDIT_SELECT_ALL, "&Select All"
        Set Control = ControlSelect.CommandBar.Controls.Add(xtpControlButton, ID_EDIT_SELECT_OBJECTS, "&Select Objects")
        Control.Enabled = False
        Set Control = ControlSelect.CommandBar.Controls.Add(xtpControlButton, ID_EDIT_SELECT_MULTIPLE_OBJECTS, "Select Multiple Objects")
        Control.Enabled = False

and I want to disable by using the "FindControl".
I try to use syntax like this :

RibbonBar.FindControl(, ID_EDIT_SELECT_OBJECTS).Enabled = False

turns an error like this:
"Object variable or with block variable not set"

what's the solution .. Please help.
I want to disable by using the function click on the CommandButton

please help

thanks for the help.
contained the same error when I use the event to another object, and errors like this: "Object variable or with block variable not set"

but I've found a way to use commandbars_update:
thanks in advance.

if you can, use the click on CommandButton?