I think you should talk to her pediatrician about this. If she is wetting at night and during the day there very well could be a medical condition causing this.
The less stressful the situation is, the less anxiety she will feel, making things worse. Definately take her to the doctor. She could have a real kidney problem. In the meantime, does she get plenty of water? (Cranberry juice is good for the kidneys too.) Also, I would keep a change of clothes with her wherever she goes, so she can keep her dignity if she has an accident. I honestly believe punishment is the wrong way to go.