The formula contains a syntax error
iMac, iOS 7.1.1
iMac, iOS 7.1.1
It's hard to say from your screenshot, but it appears you are either attempting to make a cell reference itself, or the reference is empty.
There is no need for the parentheses since algebraic hierarchy will result in the same answer.
Capture the row and column data, post a more descriptive screenshot, or describe the required calculation in greater detail.
The formula contains a syntax error