7 1/2 Lab stud wont breed

Question
7 1/2 yr old stud won't breed 4 yr. old female, he has never bred before shows no interest won't even play with her she is well in to her heat cycle in fact on her way out in a few days. she's had litters before she knows whats going on. what is his problem

Answer
As a beginner at this age, he is not likely to breed. Next time, if you plan to use him you might want to consider AI'ing.
Sorry I can't be of more help but dogs become established by the time they are five years old. I have seen many attempts at breeding beginner males after that age and few successes.
Good luck
Cindi