Problem with Exchange Monitoring

Hi,

I'm evaluating build 7101 of OpManager and on the whole it seems to work quite well. However, I'm having a problem getting the monitoring of our Exchange 2003 server to work correctly. Every time I try to test one of the Exchange monitors I always get a message back saying the monitor did not respond to the test request. I've tried the following to try and fix the problem:

I've triple checked the logon credentials and they are correct
I've checked the permissions for DCOM & WMI on the Exchange server and they are correct for logon I'm using
I've run wmiadap /f on the Exchange server but still no luck

Is there anything else that I'm overlooking/can try?

Cheers

Joe