leaking break fluid

i wappd to stoptech stage 2... instaled yesterday.. everything i aesome its just. im leaking brake fluid from my front left line.. i double checked all the lines... i bled it toay and it was fine but when i when to the strore prolly 12 hurs later the pedal becae soft again... good thing the store was only 3 blocks down.... any suggestions.... -_- sorry i didnt serarch first... i have a tri to norcal tomorro and i need a solution...

maybe i shouldve used thread locker tape(sorrry i ont know what it calle of the top of my head)

thanks.