Good day!

My name is Platak and I am currently working on some spreadsheets, surprise! Even though I am somewhat 'handy' with regards to Excel coding, I do find myself lost getting to certain outcomes and would like to utilize this forum for those moments. Thanks for all the help in advance!

Problem:
I would like the 'calculating' cell (C1) to only calculate when one out of the two variable cells (A1 and B1) contain data.

My attempt:
C1: =IF(A1,B1="","",A1+B1)

This does not seem to work. I have tried the search function on this forum which did not quite lead me to find this particular problem. Your help is much appreciated!