channel not found for reference 'cf-rtmp' in destination 'artgallerydataservice'

I have followed all the steps given in http://www.adobe.com/devnet/coldfusion/articles/data_app_print.html tutorial
I am using coldfusion 8 with multi server .. I have also installed lcds 2.6 and using flex builder 3 ..
Whenever i am running this sample getting error Severity and Description
channel not found for reference 'cf-rtmp' in destination 'artgallerydataservice'.
I am unable to resolve this problem please help me ..