upgrade 1.5.8 to 1.5.16 - gallery up but blank after login

[steakfries]

Upgraded test instance, Gallery is up, but no admin functions as I get a blank screen after login. Read through the countless pages of similar posts, re-read and re-read documentation, but didn't find a solution, though its probably there somewhere.  Update script ran fine. Tried many browsers, many machines. I am using /bridge/ad.inc.php which works fine on production machine. Permissions are ok.  I would rather pm the site link if anyone is interested or has any thoughts.

[Αndré]

I am using /bridge/ad.inc.php

1. Such a bridge file doesn't exist in the official Coppermine package
2. If you get a blank login page, you don't get it from Coppermine, but from your bridging app, as Coppermine drops its own login feature in that case