There are a number of differences between the various Axis versions which introduce incompatibilities of various kinds. I've done some investigating to check this:
Axis 1.1 and SDK 1.0a work together fine, both in client and service configurations
Axis 1.2.1 and SDK 1.0a works OK for a service, but the client code has problems because of a deprecated constant
Axis 1.2.1 and SDK 1.0b works OK for a client, but the service code has problems because of an issue with optional non-nillable elements. This can be fixed by regenerating the SDK, but Axis 1.2.1 has problems doing this due to the way it handles imports.
I've now started working with Axis 1.3, and have generated all the code again from wsdl2java, and added the bridge and implementation classes. The resulting jars work fine in client mode, and I'll start testing them in a service later today. If this works, then perhaps the best thing to do is to skip Axis 1.2.x and go straight to Axis 1.3.
The only niggle is that Axis 1.3 generates the classes "properly" (that is, with names like CreateGroupRequest and not _createGroupRequest) which means existing code will need to be updated.