Oracle JDBC Problem SQLSTATE (99999) vendor code (17004)

Hi, we use an Oracle T4 and dbvisualizer Pro (actual Version). On some Querys/Tables (for. e.g. in dbvis show "Primary Key" or use "Navigator") we wait a lot of time (5-10 Minutes). or breakt the query (stop). There is no Problem with the Oracle Database (respond times are well) but on the dbvis debug Window we can see some problems like this: SQLState(99999) vendor code(17004) java.sql.SQLException: Invalid column type: getBLOB not implemented for class oracle.jdbc.driver.T4CRawAccessor at oracle.jdbc.driver.SQLStateMapping.newSQLException(SQLStateMapping.java:69) at oracle.jdbc.driver.DatabaseError.newSQLException(DatabaseError.java:138) at oracle.jdbc.driver.DatabaseError.createSqlException(DatabaseError.java:185) at oracle.jdbc.driver.DatabaseError.createSqlException(DatabaseError.java:252) at oracle.jdbc.driver.DatabaseError.createSqlException(DatabaseError.java:260) at oracle.jdbc.driver.GeneratedAccessor.getBLOB(GeneratedAccessor.java:1011) at oracle.jdbc.driver.GeneratedStatement.getBLOB(GeneratedStatement.java:426) We are sure we use no Blobs/Cbobs in our Scheme. Our Oracle specialist (unfortunetely not in our company) thinks there is a problem with the jdbc driver (we try ojdbc6+7 with different java Versiions) with hibernate and "initialstatusfor" or Name is incorrect. Now i am not a Oracle/SQL Specialist and do not know what we can do now. Is there anyone who can help? Thanks and best regards Stephan technical background: We use Windows 7 Prof., dbvis 9.x (dif. Versions), Oracle is T4 12.1.0.2 and we try different Connections Hooks like ALTER SESSION SET optimizer_features_enable='12.1.0.2.0' ...or 10.1.0.2.0 or... PS: i speak more german than english :)