Hi,
did you find a solution to your problem? I have stumbled across the same one i think.
If i test the Service i get the same Error, but if i just use host:port/nwbc in my url it does open something that looks like the business client. I am not able to change my theme there tho.
Regards,
Karl
EDIT
I found a solution for my problem. By redirecting the transaction /nwbc from /bc/nwbc to /bc/ui2/nwbc i managed to get the client with my theme. Now my only problem is that i cant upload an image as background. When i upload one once i publish it it disappears.
Regards
Karl