How big is the male?
What temperatures do you keep him at?
Have you tried pairing him as soon as the female sheds?
Ever try leaving the females shed in with her and then introducing the male?

Are you feeding him and then trying to pair him, or are you giving him rest after feeding?
Are you pairing him after the female just ate, or are you giving her time to digest a bit?
Are you leaving him in with her when it's obvious she's not willing?

There's a ton of things that can effect whether a pairing will happen or whether it won't.
Timing is important, there are times that they just won't be locking up, it's part of the learning curve of breeding these snakes.