Index '%1' can not be clustered

Error constant SQLE_CLUSTERED_INDEX_NOT_ALLOWED
ODBC 2 State 42000
ODBC 3 State 42000
Parameter 1 Name of the index that could not be made clustered.
Severity 16
SQLCODE –878
SQLSTATE 42W74
Sybase error code 13889
Probable cause

You attempted to create a clustered index (including key indexes) but the new index cannot be created, for example, because the table already has a clustered index.