Hi,

I am trying to write a formula which is collating data from 12 workbooks. But i only want it to apply if there is data greater than zero in the cell. The formula I have written so far comes back with errors but I can't find what the error could be unless I'm missing something blindingly obvious.

This is the formula -
=SUM('[Monthly Prompts PB&OS - 001 - Jan 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 002 - Feb 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 003 - Mar 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 004 - Apr 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 005 - May 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 006 - Jun 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 007 - Jul 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 008 - Aug 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 009 - Sep 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 010 - Oct 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 011 - Nov 19.xlsx]Sofia'!C56+'[Monthly Prompts PB&OS - 012 - Dec 19.xlsx]Sofia'!C56)/(countif(('[Monthly Prompts PB&OS - 001 - Jan 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 002 - Feb 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 003 - Mar 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 004 - Apr 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 005 - May 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 006 - Jun 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 007 - Jul 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 008 - Aug 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 009 - Sep 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 010 - Oct 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 011 - Nov 19.xlsx]Sofia'!C56,">0"),('[Monthly Prompts PB&OS - 012 - Dec 19.xlsx]Sofia'!C56,">0"))