Tomcat 5.0, Connection Pooling and JNDI Datasource

Got some problems setting-up intellij idea, tomcat 5.0 and connection pooling like http://jakarta.apache.org/tomcat/tomcat-5.0-doc/jndi-datasource-examples-howto.html

please view the attached file first.

Application context: /netq
web.xml & context.xml are as in the howto...
web.xml and netq.xml (a generated file created by idea, can't edit it) are parsed, context.xml not.

when i start tomcat in idea (Run -> Tomcat Server):
Cannot create JDBC driver of class '' for connect URL 'null'

so, how do i edit the netq.xml?

greets

bachi