Try this:

=IF(COUNT(A1:B1)<2,"",A1-B1)

Biff

"Tufail" wrote in message
...
hello,
i have some problem which i mentioned is as under:

A1 B1(this cell has vlookup formula) C1(result)
1000 900 =SUM(A1-B1)

#VALUE! error is coming out if B1 is empty otherwise is ok.

thanks in advance.