I built a spreadsheet which contains the following formula:

+IF(R2<Summary!$G$2,1,MROUND(DATEDIF(Summary!$G$2,R2,"d")/30.5,0.5))

This is to calculate the number of months (to the half month) between the 1/1/12 and the Early Termination date of the lease.

Some of my colegues that need to use the sheet are getting errors for this formula. It is most likely due to an addon I have that they do not.

Is there a way to either:

Determine what addon the need?
or
Fix the formula to do the same thing without needed the addon? (Perferred)

thanks