Software Deployment

I'm trying to package Olympus DSS Standard 1.0 dictaphone software but not having much success. If I use the .msi file provided and manually go through the steps, I have no issues. However, if I either directly edit the msi or apply a .mst to accept the agreement and enter the licence key then I do have issues.

When I directly edit the .msi and change those properties I can manually go through the steps and it prefills the options and installs ok but if I use a silent /passive or /quiet parameter the install just finishes but doesn't show. If I create a transform with those properties it prefills the step-by-step options but fails saying invalid serialnumber. If I do a silent install with the transform it installs ok but is unable to play the dss file types (the play features are just greyed out), it seems like it must be missing features or something.

We are running Windows 2000. Having this automated and silent is a must at our company.