Problem with TextwriterTraceListener

Hello,

Using a custom tracelistener inherited from TextWriterTraceListener, I have
problems on a server.
No trace file is created and no trace are written.
I try our normal program based approch to add our listener to listeners
collection then the declarative way in web config unsucessfully.
We create the listener in the App_Start HTTP handler and add it there in the
collection.
How to check that our listener is added to listener collection.
This code is running perfectly on other 2003 servers, what could be the
reason for this problem ?

Thanls for help.
CS

WT