Index match with if

Any help would be greatly appreciated.

Currently I am getting the correct answer but I cant keep this part in the code as it is unreliable looking up a specific cell reference

    IF('Date of Last Turn'!C79>='Date of Last Turn'!E79

This is the whole piece of code

    {=IF('Date of Last Turn'!C79>='Date of Last Turn'!E79,INDEX('All Data'!$E$3:$E$5000,MATCH(2,1/(($H$5='All Data'!$D$3:$D$5000)*($G11='All Data'!$C$3:$C$5000)))),INDEX('Date of Last Turn'!F8:F4978,MATCH(2,1/(($H$5='Date of Last Turn'!B8:B4978)*($G11='Date of Last Turn'!A8:A4978)))))}

If anyone could help with this it would be very helpful I have tried a couple of different ways of including the match and index but I keep getting error messages