It is hard to tell with the information provided, it may be easier to help you troubleshoot if we had more a description of what the formulas are doing and perhaps a copy of the formula, if possible, and the resulting error/values. However, if they are numeric calculations, a common problem would be that the check box "Treat blank values as "0" in calculations" in the field properties not being checked would cause calculations to fail. Beyond that, it is hard to say without more information.
Here is what the formula does in my test. Is this supposed to be the final result?? Or should the Data Element fields contain that text as well?