Unexpected end of header


I am a newbie in RT, using v3. When I try to use rt-crontool for sending a
comment in case of overdued tickets, I got an error instead. Command I use

/var/rt3/bin/rt-crontool --search RT::Search::ActiveTicketsInQueue
–search-arg test --condition RT::Condition::Overdue --action
RT::Action::Notify --action-arg All --template-id 6 --verbose

and system is responding this way (taken from messages log):

Apr 10 12:37:01 rt RT: No transaction object handed to
Apr 10 12:37:01 rt RT: error: unexpected end of header

When I use an action SetPriority with an argument f.e 60, everything works
as expected (overdued tickets get requested priority).

Can anybody please help me to solve my problem? I tried to find something
about rt-crontool, but it is not documented in v3 manual. I also failed to
find relevant info in list history. I am not experienced enough in Perl to
find solution (maybe different syntax?) in code.

Thank a lot,