qat not shown on one of ten computers

[Robin]

I have the following XML entered in the Usysribbons table which is
distributed with runtime ACCDE/ACCDB. The qat shows properly on 9 of the 10
machines but the one machine that is acting as the "server", has both the FE
and the BE file, does not show it. Only a non-functional Undo/Redo shows
instead.

<customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui">
<ribbon startFromScratch="true">
<qat>
<documentControls>
<control idMso="Undo" />
<control idMso="Redo" />
<button idMso="Cut" />
<button idMso="Copy" />
<button idMso="Paste" />
<button idMso="Delete" />
<button idMso="FindDialog" />
<button idMso="PrintPreviewClose" />
</documentControls>
</qat>
</ribbon>
</customUI>

I've apparently removed any callback instructions from any module when I was
tracking down a crashing problem a couple days ago. So the two questions are:

Is this code running properly because access 2007 runtime can execute it
alone without the call back instructions?

And perhaps more importantly why doesn't it work on the machine where both
FE and BE are present?

I have the default ribbon set to the qatForms which is the name for the
above XML code. And the installation was performed on all ten machines on
the same day using the same installation file, via usb travel drive.

Thank you,
Robin