What's wrong with my Spark & openfire

I installed openfire3.7.0 on my server2003 with redfire370.3

Then I downloaded the redfire-plugin.jar into Spark/plugins.

The problem is:

When I try to share my Desktop to somebody,I click the button on my Spark

He recived a string like this :

http://null:7070/redfire/screen/screenviewer.html?stream=screen_share_42c31760

http://null:7070/redfire/video/video320x240.html?you=linxin&me=linxin&key=b9434f 57

Can somebody help me ?

Please use the version 0.7 of redfire-plugin.jar found here