CMP EJB 1.1 does not work in Portal

I am part way through a migration of a Portal from V5 to V6 and I have run into a problem with CMP EJBs. I have a combination of 1.1 and 2.x EJBs for various reasons but they are all stored in a 2.1 EJB module, because of which I have a V5 datasource defined. When run under WASv6 without Portal this seems to be fine and all the EJBs function as expected. Under portal accessing the 1.1 EJBs results in a huge stack trace:

[06/02/07 12:41:36:406 GMT] 0000006d J2CUtilityCla E J2CA0036E: An exception occurred while invoking method setDataSourceProperties on com.ibm.ws.rsadapter.spi.WSManagedConnectionFactoryImpl used by resource Polaris EJB Data source : java.lang.NumberFormatException: For input string: ""

at java.lang.NumberFormatException.forInputString(NumberFormatException.java:63)

at java.lang.Integer.parseInt(Integer.java(Compiled Code))

at java.lang.Integer.<init>(Integer.java:633)

at com.ibm.ws.rsadapter.spi.WSRdbDataSource.<init>(WSRdbDataSource.java:522)

at com.ibm.ws.rsadapter.spi.WSManagedConnectionFactoryImpl.setDataSourceProperties(WSManagedConnectionFactoryImpl.java:1762)


....

[06/02/07 12:41:36:469 GMT] 0000006d ConnectionFac E J2CA0009E: An exception occurred while trying to instantiate the ManagedConnectionFactory class com.ibm.ws.rsadapter.spi.WSManagedConnectionFactoryImpl used by resource jdbc/PolarisEJBDS : java.lang.reflect.InvocationTargetException

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java(Compiled Code))

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java(Compiled Code))

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java(Compiled Code))

at java.lang.reflect.Method.invoke(Method.java(Compiled Code))


.... + much more

All of the work that I have been doing so far has been with RADv7 and the above trace was produced by accessing the JNDI Explorer view in the Universal Test Client.

The problem does not seem to affect the 2.x EJBs but I am confused as to why the problem does not occur in straight WAS but does in Portal?

Any help would be greatly appreciated,
Regards Gareth.