Just finished kegging and force carbing my brew in my new cornie. All going well and after clear up decided to try a sneaky sample. It came with a pre assembled party tap and try as I might I can't get it to seal properly on the keg. The ring clicks into place but beer is gushing out from under the black beer out fitting. Is there something I am missing or do I have a faulty tap? Any help much appreciated, don't want to lose any of this brew, It's my best yet!!