Index and match formula

[NadoDude]

I am using the following array formula to display the last event date for a record. The array is correctly displaying the dates for the records that match, however, if there is no match on the IDWELL worksheet, it is diplaying 12/24/2006.

Is there a way I can tell the formula to display "NA" if there is no match?

{=INDEX(IDWELL!$P$2:$P$2499,IF(ISNA(MATCH($A2&MAX(IF(IDWELL!$I$2:$I$2499=$A2,IDWELL!$P$2:$P$2499)),IDWELL!$I$2:$I$2499&IDWELL!$P$2:$P$2499,0)),3,MATCH($A2&MAX(IF(IDWELL!$I$2:$I$2499=$A2,IDWELL!$P$2:$P$2499)),IDWELL!$I$2:$I$2499&IDWELL!$P$2:$P$2499,0)))}