I have a tool with the following fields.

studentDOB - a date field tracking birthdate

studentDOBMonthName - a calculation field returning text result - MonthName (studentDOB)

studentDOBMonthNumber - a calculation field returning number result - Month (studentDOB)

The DOB field works fine. But the other two fields return question marks.

This is an FMPA 17 file, hosted on FMS17, accessed on macOS 10.14.2.

Any help would be appreciated.

Possibly try - MonthName ( GetAsDate ( studentDOB ) )  and Month ( GetAsDate ( studentDOB ) )

If Month (studentDOB) returns an error, then my guess would be that studentDOB does not contain a valid date. What is a valid date is determined by the date format being used by the file: this could be either the format of the current system or the format of the system that first opened the file, as selected in File Options.

Problem solved. As comment suspected, the problem was with the date field. The dates appear to be correct, but changing the format corrects the problem in the other fields. Thanks to both of you for your replies.