Use If(ISNUMBER(Match to compare two columns from one sheet with two columns in another

Try it like this:

=IF(AND(ISNUMBER(MATCH('WO Operations'!A5,Schedules!$A$1:$A$4000,0)),ISNUMBER(MATCH('WO Operations'!B5,Schedules!B5))),"",'WO Operations'!A5)

Hope this helps.

Pete