Ok I have changed it slightly but still dosen't work.
=IF(OR(AND(COUNTIF(D18:E18,"B")>1,Dutch!B18<=5,$U$1>3,$S$1<=Controls!$B$1),AND(COUNTIF(Dutch!D18:E18,"A")>0,$U$1>3,$S$1<=Controls!$B$1)),"BACK","")
I get "BACK" when "A" is in the range, but when "B" is in the range and Dutch!B18<=5 I don't get "BACK"