[Can't register vda machine in trusted domain]

Have you ran the citrix health assistant and see what it says it failed on

[Full Admin but Permission Denied]

I had this exact same issue a few weeks ago and I assume like others it was because you upgraded to a new version of xenserver. I've read that before you do an update, you need to disconnect the site from studio before you do an upgrade or it gets corrupted because a new class ID is created and it messes with the previous one.

 

In the end I had to re create my studio from scratch. Luckily if you have snapshots of all vms and policys, its only around an hour-2 to fully re configure.