[Koha] Searching By Barcode in koha

Dear All, In the cataloguing Module I would like to search by barcode so that it retrieved an exact copy of an item. At the moment if I search by barcode e.g. AUP 100, the cataloguing Module returns: AUP 100, AUP 1001 AUP 1005 AUP 1006 and so on I need the system to pic the exact barcode not the.way it is displaying the results Thanks in advance Sher Afzal