[TYPO3-english] No Backend, only: <html><head></head><body></body></html>

Sun Nov 20 08:46:09 CET 2011

Hi,
I had to setup a new TYPO3-Server (4.5.7), now running under Debian 6.0.3.
I restored my old pag, frontend ok, no problems with the database.
But Ican't get into the backend. No chance to login, I only receive: 
<html><head></head><body></body></html>
I can't find any messages under /var/log/apache2, even with Warnlevel 
Debug. Same when I wnat to reach typo3/install.
Schon mal herzlichen Dank!
Ciao
Tom