Manual Transmission - tranny pops out of 1st

i got my brand new trans put in. and went to put it in fist to take off and the thing pops out of first gear. so i pressed in the clutch and went 1st gear 2nd gear and so on till it stayed in first. does this crap every time.any suggestions on why its doing this. the tranny shifts great in every gear its just trying to take off thats giving me trouble

Check the shifter but if it is 1st sounds like it could be clutch related. It has billet keys in the 1/2 slider so you shouldn't have to worry with that. I still think shifter but what clutch are you using? Did you use a shim behind the slave? Did you replace all of the hydraulics? What shifter?

Amber