This has now been corrected for you. There seemed to be an instance of the AutoDJ running in the background already for some reason. We just killed that instance and restarted the server and the stop button is available again for you now.
I tried setting up my SAM Pro using the settings above in your example, and it still does not work to turn off the AutoDJ -- I get an error each time. And you talk about running a Shoutcast 2 server, but using Shoutcast 1 protocol settings seems a bit weird.So I tried a few other settings without success. We need to have the server looked at the the issue resolved.