Actually, I just discovered that I have an even bigger issue beyond the Director:: thing. First off, my SQL needs to be a bit more involved. I don't HAVE an ID for the Client in the ProjectPage table. Just the ClientName. So I need first to pass the ClientID in to the Clients table, get the ClientName there, and then get the Projects from the ProjectPage table which have this ClientName. How to accomplish??
Director::urlParam() points to an array such that the url equals www.yoursite.com/URLSegment/Action/ID/OtherID so unless you tell SS which one is 'ClientID' it has no idea!
How are you trying to pass the client id? eg if you are doing www.yoursite.com/clients/show/12 you would need to use Director::urlParam('ID') (as URLSegment = clients/, action = show/) or if you are using PHP Query strings so like www.yoursite.com/clients/show?clientID=12 you can get the clientID via $_GET['clientID'];