Welcome to the forums.

I'm a commerical developer and we have the exact same problem with several of out clients.

The solution: It must be installed by an administrator. At our client sites, an administrator has to physically sit down at each machine, login with the admin account, install our product, and then log back out again.

Given the way they have there company machines set up, that is the only way that anything can be installed.

It sounds like you are facing the same thing.