Be sure the runserver file for your current server is located in $SYBASE/$SYBASE_ASE/install/RUN_servername.
Verify that the file is still named RUN_servername, where servername is the name of the old server. The servername must appear exactly as it appears in the interfaces file. The RUN_servername file for a server SYBASE is called RUN_SYBASE. If the RUN_servername file for your current Adaptive Server is named, you must change the name during the upgrade process.