Issue with streaming target

I try to forward a stream to a custom rtmp streaming target, but can’t get it working.

The target is: rtmp://1_3j2gngmn.p.kpublish.kaltura.com:1935/kLive?t=a4271cfa

Whatever I try (using dest. app. name / app. instance / stream name) it fails. I guess that WSE isn’t able to handle “?” and “=” in the target’s name. Any idea how to get this work?