vision students not visible after imaging

[Dongemond]

Situation:
installed netop vision teacher[latest build] and 1 student, i imported the student into the teacher and he appears in the classroom ok. Then i made a image of the student and installed the image on the rest of the clients in the class and add them in the classroom. The first student [that i used to make the image] appears in the classroom, the rest gives a blank [black, disconnected] screen. What can be the problem?

All clients are xp with latest updates

Greetings, Andy
update: the error was caused by the fact that the ipnumber in HKLM\SOFTWARE\Netop\Vision\6\Configuration\Browser \interface was the same on all computers [because i imaged them]. I cleared the registery-key with a grouppolicy preference and the clients are visible now