my bullmastiff has just had a false pregnancy she was served as normal but there was no no pups at the end of the day the stud we used was only 11 months old we was told he was proven at 9 months then we found out the bitch only had 1 pup he is a fine dog and he suits are bitch should we wait till he gets older and try again or is this the stud dogs falut as my bitch has had a litter before from a different stud  and will she ok to breed again or should she be spayed

If she had even a single pup it proves that he was fertile. Litter size is usually dictated by the bitch - either by the number of eggs released or how many are ready for fertilisation at mating. It could be she was mated too early or too late in her season for optimum litter size.

I'd be concerned about using a stud dog of this breed who hasn't been hipscored, as HD is a big problem in your breed, so I'd wait until he's been satisfactorily scored before using him again. Of course, your bitch has a satisfactory score, or you wouldn't have bred from her before. If she hasn't been scored either, get that done before you consider taking another litter from hre.
:)

I agree with JG all the bitches from my litters all had 9 puppies.