Problem to get mac address table from 1920 HP switch

Hello, I have problems to get mac address table from switch HP 1920. I only can get one o two mac addresses. If I launch a snmpwalk command to these switches from CLI, I get the next error: Error: OIDs are not increasing If i execute the snmpwalk command with -Cc, it works fine. How can I configure in NAV the -Cc option? Thanks in advance.