I want to use the new ModelAdmin functionality. Are you sure it works in the trunk as sminnee describes in http://doc.silverstripe.com/doku.php?id=modeladmin ? Using the code on that page I end up with an empty screen on the url admin/catalog.
ModelAdmin is all on trunk. To make it work you need cms/ sapphire/ and jsparty/ all in the latest trunk releases. If you have a blank screen check your PHP error log on your server and see what the problem is