As you are probably aware Animal Form retains the last form that you used. I have ever been able to achieve these results by acquiring a higher level form and then stoning away the skill or removing +skill jewelry. Trying to use animal form after that will often result in the "you need XX skill" message. There is already a problem report in the system on that issue. If you need an immediate solution I would suggest submitting an appeal and the GM should be able to resolve the issue.