What exactly do you mean by "doesn't work"?
Is an error output?
Does the command fail silently and just returns a prompt?
Does the command hang?
Is this a classic "dump database <dbname> to <device>" or a more recent variant such as a cumulative / incremental dump?
Local or remote dump?
If the command is hanging, output of dbcc stacktrace on the hanging spid may be helpful:
set switch on 3604
go
dbcc stracetrace(<spid>)
go
ASE version would be helpful.
-bret