Sybase CEP Server must be running in order for Sybase CEP Engine to work. To check if Sybase CEP Server is working, start Sybase CEP Studio, which automatically tries to connect to Sybase CEP Server.
If Sybase CEP Server is running properly and the current workspace is connected, the workspace icon (displayed in the left upper pane of Sybase CEP Studio) looks like this: 
If Sybase CEP Server is not running, or if Sybase CEP Studio is not able to connect to it for some reason (such as due to a networking problem) then your current workspace appears in italics, with the words "not connected" next to it, and the icon looks like this: 