VBA and ISNA# Format

Hi, I have this piece of code that returns a value with #NA sometimes when there is no value. How can I make this #NA not show when there is no value.

Here is the piece of code.

.Offset(3, -2).FormulaR1C1 = "=LOOKUP(2,1/((R27C7:R" & lngLastRow & "C7=R[-2]C[2])*(R27C28:R" & _ 
lngLastRow & "C28=R[1]C)),R27C11:R" & lngLastRow & "C11)"

Thanks...