[Zope] No Database-connection with Z SQL Methode

Hello, i use zope2.0b3 with MySQL as Database. The ZMySQLDatabase-Adabter works fine. Now i want include a SQL-Query with Z SQL-Methode. But if i do this, Z SQL-Methode give the error-msg : " no database connection found. please connect ... " Is this a problem of the beta3, how can i debug the problem ? regards A.Spanke