Are you using Amerun to open the model?
If you are, your colleague needs to have gone into Simulation mode in Amesim in order to compile the model.
Then you would be able to open and run it in Amerun.
If you are using Amesim, I'm not sure what is going on and I advise you get in touch with GTAC to raise an incident request. See this post for details about using GTAC.