XF 1.5 server being moved, host asked me to test, can't login to admin acct?

[sross]

I'm one of the wiredtree guys being migrated to Liquidweb. They are wanting to migrate me soon. They placed my sites on the new server and asked me to test everything before the final changeover. On the new server everything seems fine with normal user accounts. However, when attempting my admin login, i enter my correct password and it acts like it is about to log me in but then kicks back to the site, not logged in. I've tried multiple browsers. I'm not sure why this is happening, thanks for any help.