Why Does My Shifting Skip?

My 1993 dodge ram was skipping second and so they the mechanic said it was a cable. Ok so they said they fixed that problem. I drove it home and looked underneath, the next day and it was leaking transmission fluid. It wasn't leaking, before I took it to the mechanic and drove it a mile home. What could they have done to cause leaking transmission fluid. I guess the seal is broken and I've asked them for an estimate for fixing the seal. I have no idea how much it would be but I'll take it back there 'cause they're the best mechanics in Victorville, CA but I don't know, this seems funny, 'cause I just got my van back. donna_rdly@yahoo.com