TF727 will not up shift to 2nd on launch

Went back to the track last night, with good results. After the first full pull that resulted in the trans NOT shifting into second, I went back to the pit and checked the trans fluid. It measured a little low on fluid. I added about 1/2 qt or Type F and took it back out. It ran good with good solid shifts. 1.725 60' and 7.5 @ 91.5 MPH.
We'll see what happens in future runs.

Thanks guys!