[Maximo]

I agree with posting in the breeder's forum here.

I don't have any experience breeding, but I believe situations like this are why good breeders always recommend working with an experienced mentor, and with close vet supervision.

A vet should examine the dead puppies to help determine the cause of death -- especially if you intend to breed your dog again. My understanding of dog pregnancy is that the dog will shows signs long before birth is imminent, more than 8 hours, for instance. If your girl did not show any signs, then there was probably a health problem. Your girl should be thoroughly checked by a vet -- not just a standard pet exam -- before you consider trying to breed her again.