Are we to assume that this is the predicted whelping day? I hope that, in the meantime, pups were born and all and the dam are fine. Can you feel pups moving? Check heartbeats of pups, and have an ultrasound of the bitch to see pups. At least one pup is probably dead by now, if not already delivered.

Sitting and waiting is not going to get you a live litter. You need a veterinarian's help, up close and personal. Fast.