Problem with sievefilter forwarding

[ratatouille]

Hello!

dovecot --version 2.2.36 (1f10bfa63)

I defined a sievefilter

require ["copy"];
# rule:[weiterleitung]
if header :contains "to" "user at bitclusive.de"
{
	redirect :copy "otheruser at gmail.com";
	stop;
}

It doesn't work and I don't know why. I can define a vacationfilter
that works fine.

Can I debug this somehow and can somebody here explain what
is going wrong?

Kind regards

  Andreas