=IF($S3=1,LOOKUP($W3,Ltable!$F$11:$F$15,Ltable!$G$11:$G$15),IF($S3=3,LOOKUP($W3,Ltable!$F$11:$F$15,Ltable!$G$11:$G$15),"0"))
THIS CODE WORKS FINE , how do i get it to only work if w3 has a value in it otherwise display 0

Currenlty if w3 is blank it displays #n/a but if w3 has a value in it it calculates the score.