Ribbon.InvalidateControl not working on PPT 2010 - vba

Question

I have a an add-in within the Insert Ribbon of PPT 2010. Basically what I want to do is to make a selection in a combo box, then run a macro, then set the combo box to blank. Unfortunately I´v been unable to clear the selection.
I have searched all over the web with various methods and nothing helps. Hope someone can help.
My XML
<customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui" onLoad="VirtusInitialize">
<ribbon>
<tabs>
<tab idMso="TabInsert">
<group id="CustomGroup1" label="Sticker">
<box id="box1" boxStyle="horizontal">
<comboBox id="ddlItem" label="STICKER 1" onChange="Sticker1">
<item id="BU" label="BACK UP" />
</comboBox>
</box>
</group>
</tab>
</tabs>
</ribbon>
</customUI>
VBA code:
Private MyRibbonV As IRibbonUI
Public Sub VirtusInitialize(ByVal ribbon As Office.IRibbonUI)
Set MyRibbonV = ribbon
End Sub
Sub Sticker1(ByVal control As IRibbonControl, text As String)
'do stuff
MyRibbonV.InvalidateControl ("ddlItem")
End Sub

Answer 1

Alternatively use a Dropdown control instead of combobox
I found some information here, at least enough to get started...
http://gregmaxey.mvps.org/word_tip_pages/customize_ribbon_main.html
Use XML like:
<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui" onLoad="VirtusInitialize">
<ribbon>
<tabs>
<tab idMso="TabInsert">
<group id="CustomGroup1" label="Sticker">
<box id="box1" boxStyle="horizontal">
<dropDown id="ddlItem" label="STICKER 1"
getItemCount="GetItemCount"
getItemLabel="GetItemLabel"
getSelectedItemIndex="GetSelectedItemIndex"
onAction="Sticker1" >
</dropDown>
</box>
</group>
</tab>
</tabs>
</ribbon>
</customUI>
And VBA callbacks:
Private MyRibbonV As IRibbonUI
Public Sub VirtusInitialize(ByVal ribbon As Office.IRibbonUI)
Set MyRibbonV = ribbon
End Sub
Sub Sticker1(ByVal control As IRibbonControl, id As String, index As Integer)
'do stuff
Select Case index
Case 0
Case 1
'do stuff
Case 2
'do stuff
End Select
MyRibbonV.Invalidate
End Sub
'Callback for ddlItem getItemCount
Sub GetItemCount(control As IRibbonControl, ByRef returnedVal)
'puts 3 items in the dropdown and triggers the GetItemLabel
returnedVal = 3
End Sub
'Callback for ddlItem getItemLabel
Sub GetItemLabel(control As IRibbonControl, index As Integer, ByRef returnedVal)
Dim str$
Select Case index
Case 0
str = " "
Case 1
str = "BACK UP"
Case 2
str = "GO FORWARD"
End Select
returnedVal = str
End Sub
'Callback for ddlItem getSelectedItemIndex
Sub GetSelectedItemIndex(control As IRibbonControl, ByRef returnedVal)
'not used
End Sub
'Callback for ddlItem getText
Sub GetText(control As IRibbonControl, ByRef returnedVal)
'not used
End Sub
'Callback for ddlItem getItemID
Sub GetItemID(control As IRibbonControl, index As Integer, ByRef id)
'not used...
End Sub

Answer 2

try this:
Sub Sticker1(ByVal control As IRibbonControl, text As String)
'do stuff
Call MyRibbonV.InvalidateControl ("ddlItem")
End Sub
Notice the keyword "Call" added to the original code.