Rottie Breeding

Question
I have two rotties.  I bred them at approx the age of two.  The female was a bit under two.  When they locked together they became "stuck".  We have had two heats since and are fast approaching a third.  She will not accept him.  Do you think it was from the previous "trauma"?  We are so looking forward to another litter... probably our last.  Do you have any suggestions?  Also, should we keep them apart for any length of time while she is in heat?

Answer
The getting "stuck"  is called tying,  It should last approximately 20 minutes to ensure the sperm can travel the length of the "tunnel" and fertilize the eggs.  If your female has taken a dislike to your male, you can do one of two things.
one keep them separated most of the time by a gate or door and only let them together when she is in heat.  She MAY accept him then, but only maybe.  
Two by pass the whole thing and when she is ready take them in to the vet for artificial insemination.
I had the same problem and that's what I did, because my female hated my male.  Then I got another male and she loved him and had four littlers with him.
it was love
Nancy
PS  she never did like the first male, with him AI was the only way, I wouldn't force her like some breeders do.