Excel Forumla Help Please! What am I doing wrong?

[Dan C.]

=IF(ISNA(MATCH(B1,Sheet1:Sheet2!B:B)),"No Match","Match")

This formula searches to see if (X) is on sheet 1 or sheet 2. I need it too
search sheet1 and sheet2 too see if it is on both. Anyone help?

 

[Jim Thomlinson]

=IF(OR(ISNA(MATCH(B1,Sheet1!B:B)), ISNA(MATCH(B1,Sheet2!B:B))),"No
Match","Match")

 

[Don Guillett]

=IF(ISNA(MATCH(B17,Sheet1!A:A,0)),"not on 1","on 1")&"
"&IF(ISNA(MATCH(B17,Sheet2!A:A,0)),"not on 2","on 2")