|OK - I think I have got it, but still need to know how to fix it.|
If the if formula does not satisfy any of the criteria it is doing as it is told and returning an empty cell.
=IF(E$3= "OU", Parts!$C15,IF(E$3 = "SS", Parts!$D15,""))
With this formula it either picks up the information in cell Parts!$C15 or Parts!$D15, so if it is an empty cell it is returning a 0 - hence the dash as its formatted to Marlett.
How can I get it to show a blank cell? I have tried to copy and paste extracts from the file but that doesn't really work very well. Can you suggest anything for sending more details?
Alternatively if you can simulate - I have two columns with ticks in showing the parts to make an OU and the parts to make an SS. Some parts are the same in each, some are unique to one or the other product. If you made up two columns in an excel spreadsheet with random ticks in either column maybe?
Thanks for your help