Clarification: The code using the number to filter is working fine. The code using the class identifier is not working. Any suggestions as to why the class identifier is not working?
working at www.wardnet.com
blogging at www.jamesward.ca
Check whether advocacyonline turns up in this list - maybe you just have a typo or so.
If that does not help and if you know a bit of PHP check what the function
eZContentObjectTreeNode::createClassFilteringSQLString is doing. As far as I know this is the function responsible for the class filter in most content fetch functions.