Hi there,
Have you checked your OperationsManager logs for more information and are you receiving any alerts in your Ops console?
There are a few issues which can cause this, number one being your RunAs account does not have the relevant permisssions. Post back when you have more information so we can help further :-
David Allen
http://www.inframon.com
Microsoft MVP - System Center Operations Manager 2007
WMUG Community Leader http://www.wmug.co.uk/blogs/aquilaweb