Check for the following:
The SYBASE environment variable is not set or points to the wrong directory.
(UNIX platforms) X-Windows is not configured correctly. If you are running dsedit on a remote host, make sure that X-Windows clients on the remote host can connect to the X-Windows server on your own machine. See your X-Windows documentation for more troubleshooting information. If X-Windows is not available, use dscp instead of dsedit.