power steering pulley install

i am reinstalling a power steering pulley on a 97 tbird v6 but am having troubles. i have an installer kit but when i put the bolt in and tighten, then try to tighten the nut, to press the pulley back on, i can only do about two revolutions then the bolt slips out. i have stripped one bolt doing this and am afraid the female side is stripped as well. what can i do to get the pulley the rest of the way on?

i would find a bolt that screws in without the kit first then use it with the kit mabey the bolt you are using is to short otherwise there must be a problem with the threads on the shaft on your pump!