"?" Coming Up in Calculation Field
I am sure the answer to my question is simple, I just don't have the time to keep searching for this answer. I created a simple calculation field where it calculates the difference of the input of two previous fields (eg. Field C = Field A - Field B). Instead of coming up with an answer in the Field C box, however, it just shows a "?". When I click in the Field C box, the correct calculation comes up but then it goes right back to a "?" when I do something else. Also, I use this field (Field C) for another calculation (Field C*Field D=Field E) and Field E comes out with the correct output. Why is the question mark coming up and how do I get the actual numbers to show?
Thanks in advance!