i have a leak

i recently installed a temp sensor in my trany cooler return hardline. it consists of a brass t-fitting that, after cutting the hardline, you put between the cut line. then two end caps are screw tightened down over a small piece of brass which is supposed to crush onto the line and seal it up. the problem is that fluid is leaking out of where the sleeve is supposed to seal against the hardline. tightening it down to oblivion doesnt seem to help, so im wondering if there is an apoxy or something i could use?

you might try some teflon tape.

under the crush sleeve? i used it everywhere else and thats all sealed.