Fields are not appearing in the synonyms table

[Ze0]

Hi, I am relatively new to Crystal Reports and I have a problem with displaying the fields of the synonyms tables when I connect to a new JDBC(JNDI) datasource.
If I start a new Standard Report, connections to the JDBC datasource works fine, but i cannot expand the synonym tables to show the fields.
Similarly, if I try to change the location of a datasource of a report by 'Set Datasource Location', when i update the datasource, the Map Fields dialog appears but there are no fields in the right boxes.
I dont know if this is because of Crystal Reports (XI Release 1), the driver or the CRConfig.xml file.
At the moment, this is how part of my CRConfig.xml file looks like:
<JDBC>
<CacheRowSetSize>100</CacheRowSetSize>
<JDBCURL>jdbcracle:thin156.78.96.12:1522://serverID</JDBCURL>
<JDBCClassName>oracle.jdbc.driver.OracleDriver</JDBCClassName>
<JDBCUserName>User</JDBCUserName>
<JNDIURL></JNDIURL>
<JNDIConnectionFactory></JNDIConnectionFactory>
<JNDIInitContext>/</JNDIInitContext>
<JNDIUserName>weblogic</JNDIUserName>
<GenericJDBCDriver>
<Option>No</Option>
<DatabaseStructure>catalogs,tables</DatabaseStructure>
<StoredProcType>Standard</StoredProcType>
<LogonStyle>Oracle</LogonStyle>
</GenericJDBCDriver>
</JDBC>
What may be the probable causes of my problem? And how can i solve it?
Thank You in advance.