A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Did you re-enter the formula after editing it by using Ctrl-Shift-Enter? It is an array-formula and requires special entry.
It is also possible that what you actually need is this:
=INDEX('1 entry form'!$E$12:$E$27,MATCH(1,($C12='1 entry form'!$B$12:$B$27)*($B12='1 entry form'!$C$12:$C$27)*($D12='1 entry form'!$E$39:$E$54),0))
also entered using Ctrl-Shift-Enter - but you need to use another comparison cell: I used D12 to match the entries in E39:E54.