Normally you get this error if:
1. The name is listed for sale at Afternic.com
2. You just bought the name from Namejet and there is 45 hold before you can push to another account.
I manage to push the names. What I did was I deleted first the names from the premium listings at the marketplace they were selling and then change my dns to enom's servers and then waited a while so it takes effect and then went to enom premium listing and cancelled the premium listings. After that I could push the names. Hope that helps.