The following is working that if the same item exist in G7 and in
item.xls(item!)
=IF(COUNTIF([item.xls]item!B:B,G7),VLOOKUP(G7,[item.xls]item!B:L,11,0),0).

But I have to check two sheet Item! and Stock! in item.xls. If the G7
value may exist either in Item1 sheet or in stock! sheet. So please help me
again to incorparate this changes with the existing formula
=IF(COUNTIF([item.xls]item!B:B,G7),VLOOKUP(G7,[item.xls]item!B:L,11,0),0).

=IF(COUNTIF([item.xls]stock!B:B,G7),VLOOKUP(G7,[item.xls]stock!B:L,11,0),0).