[TYPO3-dev] Front End User Registration does not show registration for new user

[John]

my website install "Front End User Registration" extension. The user 
registration page can not shown in the new server, but it was shown on 
my old server.

I copied all the files from old server and dumped the database for the 
new server. But the registration page does not show up on the new one.

my typo3 version is 4.2, and the "Front End User Registration" version 
is 2.5.24.

Now typo3 and "Front End User Registration" are same on the new server 
and the old one. But the linux, apache, and php version are different. 
Linux on new one is ubuntu 11.04 and the old is debian.
Apache on new one is 2.2.17 for ubuntu, and the old one is 2.2.3 for Debian
php on the new one is 5.3.5, and the old one is 5.2.0

Can anyone give some clue for how to solve this problem?
do I need do any configure for linux, apache, or php?

thanks.