1. I added CODE tags to your macro -- you can use the [#] incon next time to add them
2. No need to .Select or .Scroll - you can work directly on objects
3. This part 'looks wrong'
Formula1:="='Look up Tables'!Zi"
If I always = 20 then try
Formula1:="='Look up Tables'!Z20"
If not, then try
Formula1:="='Look up Tables'!Z" & i
Otherwise attach a workbook with the WHOLE macro and details