I just realized that you are using Excel 2003. IFERROR is not supported in 2003.

Try this instead:

=IF(ISERROR(INDEX(A:A,SMALL(IF($C$6:$C$12<>"",ROW($C$6:$C$12)),ROWS($1:1)))),"",INDEX(A:A,SMALL(IF($C$6:$C$12<>"",ROW($C$6:$C$12)),ROWS($1:1)))) Ctrl Shift Enter