Publish in AS3 cause ad serve to fail?

My company just upgraded to Flash CS3. We are a publisher but we also supply creative services. For some reason my superiors think that I should not publish in AS3 because it will have some effect on the ability to adserve an ad. They also told me this about AS2 but I’m certain this isn’t the case. If I’m not mistaken, the AS setting has no bearing. Can someone give me a technical answer?