probelm with package

hello ,
i get this error and i already have installed net-snmp modules

./check_snmp_isl_ciscoMDS9k-v1.1.pl -H 10.250.0.13 -C public
Can’t locate object method “new” via package “SNMP::Session” (perhaps you forgot to load “SNMP::Session”?) at ./check_snmp_isl_ciscoMDS9k-v1.1.pl line 128.