My name is Scott and I am an experienced small animal veterinary surgeon, I will be very pleased to work with you today and will try my best to answer your question to your satisfaction.
Can you tell me how the puppies are behaving, do they seem hungry?
Ok, here is what to do, have your vet check Maisie over in case there is some health problem such as perhaps she is running a temperature and so is in the early stages of perhaps a womb infection or mastitis. This could be the cause of the lack of milk ...
Very often though there is no apparent reason for the lack of milk in the mother and unfortunately there is sometimes no drug or other way to get the milk going.
If the puppies are getting enough milk they will be sleepy and quiet between feeds, if this is not the case they may be crying and restless. The bottom line is that if you think the puppies are not getting enough milk you will quickly have to start supplementary feeding. Use a dog milk substitute, you can get these form your vet or better pet stores.
Sorry there is no other course of action
I hope I have covered your question fully enough but if you would like further clarification or to talk things over a bit more then I will be on-line for the next hour or so and I will be more than pleased to continue working with you.Regards,Scott