powerpoint 2003 Slides.InsertFromFile fails when macro security V.

[Leo2]

Hi,

I have a VBA Add-in for Powerpoint 2003 that uses the
ActivePresentation.Slides.InsertFromFile command to insert slides into the
PPT file from the POT file. The POT file is located on a network drive. When
macro security is set to Low this runs as expected, with macro security set
to very high (and trust all add-ins checked) all the code in the add-in
appears to execute EXCEPT for the InsertFromFile command, no exception is
thrown, it just doesn't work. is this expected behavior and if so what is the
workaround?

Any advice appreciated!
Thanks.