Line port "Barge in"

[mrjoe]

I'm trying to implement this to allow me to barge in to the Line port from any extension on my PBX.  I'm following this guy's instructions:
http://www.obitalk.com/forum/index.php?topic=1157.msg36138#msg36138

but it says connected and then disconnects after a few seconds... it isn't tapping in to the line.

Any ideas?