this happens because of an engine bug with the error() function. unfortunately i use the error() function for outputting the demo message.

the error() function is supposed to show a message window but currently the message just gets written to the acknex.log and the engine closes immediately.

this should only happen with c-script and jcl will fix it. the release version of the plugin doesn't show a demo message (only real errors) so it shouldn't be a big problem in the meantime.