Unable to invoke my external program specified in snmptrapd.conf

[Krishna Mohan]

Dear All,
I'm able to receive traps using snmptrapd in /var/log/messages. However, I'd like snmptrapd to invoke my external program so as to alert me on receipt of trap.
In snmptrapd.conf i have written this directive
"traphandle default /usr/bin/krsna.pl"
It's a perl script which gives message "u have recved a trap" infinite times. i also has given
"traphandle default /usr/bin/perl /usr/bin/krsna.pl" as somebody suggested.
It's not working. Plz tell me how can i invoke my external program (in CLI, Linux).

Thanx in advance
Regards
KrishnaMohan