I'm running through the Tutorial here: http://doc.silverstripe.com/doku.php?id=tutorial:5-dataobject-relationship-management where you create a Google Summer of Code project directory with Student/Mentor relationships.
Admittingly, I'm changing class and field names to suit what I am using it for. The analogy is perfect for what I want.
My Project holder works, but when I go to create a Project page under it, I get a simple JS error that says: "ERROR:There has been an Error".
Not very descriptive obviously, so is there a way I can get a more detailed explaination of what the error might be? (In the CMS)
Have you got firebug installed? If you have that would hopefully be able to point out the error. The error isnt a blank page with the black text ERROR is it or is it inline in the CMS? If its a whole blank page then try putting the site into Dev mode - which will display full errors instead of the basic error page.