stripped thread on aluminum rad...how to fix leak?

[CUDA8U]

  I installed a champion alum rad and when i tightened 1 of the tranny lines it seemed stripped and now leaks,will not tighten !The threads look good on rad but it just won't tighten.I tried teflon and white thread sealer without any luck.

SUGGESTIONS?

[Chryco Psycho]

are you tlking about a female thread in the rad for the male to male fitting , have you tried a different fitting ?