Can't Communicate with Printer


We developed an application that runs in Windows.  We have installed in several of our PC and they work fine. When we installed in our customer PCs, after loading the dll, drivers and the installation of the printer, and printing a "test page" everything seems to be working ok, when we try to print from our program we get a "Couldn't connect yo printer".  We uninstalled the drivers and un-register them from the registry and tried to re-install everything from zero and we get the same result; we tried in several computers and we get the same results.

Any advice?