TC lock up WOT

Hey guys, so I've pretty much got the mcc engine tuning down pact, now where I'm scratching my head is the trans.... I can not seem to get my TC to lock up under WOT when I get on it hard from a slow roll... Now it locks just fine if I'm part of half way and once it's locked I can mat it and it will stay locked.... I hope that's made sense any help would be great