Software Deployment

I'm trying create a custom action in my product's msi file to run the Visio 2002 msi if required. (My product is a Visio Addon.) The Visio installer is located in the relative location: Visio_Pro_2002\visio.msi. But, everything I have tried has failed. It seems that the visio.msi has trouble finding its own uncompressed files. Yet, it runs just fine from the command line. The files have been copied off the Visio CD verbatim.

Please, can anyone offer any ideas about this? The goal is to package both Visio and my product on the same CD for distribution (properly licensed of course). I really don't want to repackage Visio, but just call it's msi file. I feel I'm missing something really basic here.

Thanks, Carl
C-mach Technologies Inc.