problem when deleting a class

Hello,
I gto the following error when tring to delete a class .

org.springframework.jdbc.BadSqlGrammarException: PreparedStatementCallback; bad SQL grammar [SELECT * FROM _cm3_class_delete(?::regclass)]; nested exception is org.postgresql.util.PSQLException: ERROR: relation “Domains” does not exist, caused by: org.postgresql.util.PSQLException: ERROR: relation “Domains” does not exist

please help.

thanks