Change Access 2007 to 2013 - Calculation Problems

Hello together

I have a form with some calculations in the code area. (no complicate stuff, just add, div,multiplicate).

This form works with Access 2007 perfekt. Since i have upgrade to 2013, in some cases, the form

will not calc correct my fields. Move the same db back to 2007, no problem. the db is stored in the mdb-format.

Is there someone out there with an idea what MS has changed in the back from 2007 to 2013?

Thanks

beste regards

rene