What is your webMethdos version?
Did you restart your server in order for the dispatcher to load and start automatically?
Did you make sure the broker settings are correct on IS admin under Messaging?
Did you check your dispatch.cnf file in your integration server config directory. See if it matches with your broker settings. If its not you can back up the file, get the IS down and delete it from the config folder and restart the server.
Happy New Year 2015 
#webMethods#Universal-Messaging-Broker#Integration-Server-and-ESB#Broker-JMS