I'm using this VLOOKUP formula
=IF(ISNA(VLOOKUP($A23649,WITCRX!$A$2:$C$64321,3,FALSE))," ",(VLOOKUP($A23649,WITCRX!$A$2:$C$64321,3,FALSE)))

if there is a value in the WITCRX worksheet the valued is returned however if the cell in WITCRX is blank the value returned is 0,. I don't undertand why. What do I need to change in the WITCRX cells with no value?