Like ACP Expert, ImageMan links projects to users (Expert version).
One of the users initially set up ImageMan on test computer on which Scheduler was set up with the default user.
When he set things up on his observatory computer, Scheduler was set up with his own name as user.
As the ImageMan database he had imported from his test computer did not have the new user in it's database, it could not be imported.
I will see if I can come up with a solution in a future update.
In the meantime, please run the setup wizard from scratch for each installation.