connecting between versions

I've been trying connections between versions and I've found that 6.0 to 5.1 won't work (no backward compatibility there).
Has anyone tried connecting from 6.1 to 6.0 ? Does backward compatibility exist for those?
The connections I'm making are between clients (using weblogicaux.jar from one version) and EJBs (using weblogicaux.jar from the other).
[This message has been edited by Jim Lang (edited October 17, 2001).]

Hi Jim,
All WebLogic Servers in a cluster must be the same version. Version 6.0 will connect to another Version 6.0, but not a Version 6.1 (otherwise an error message will be generated, so check your log). Different service packs on the same version are supposed to be compatible, but in practice this is not always the case (bug fixes, different access code, can lead to incompatibility).