Tweak formula to add another criteria

[Fazila]

Is there a way I can tweak this formula so it looks at both the teacher and the subject? I've tried adding AND, adding IF (sub=$a4... at the beginning of the formula but doesn't quite work.

{=IFERROR(INDEX(Cls,SMALL(IF(Teach=Sheet4!$FV4,ROW(Teach)-ROW(INDEX(Teach,1,1))+1),1)),"")}

All help appreciated.

Thanks

 

[Fazila]

anyone?