I've run into the same error. It turns out that there is a bug inside the soap parser BB is using. In my case the workaround was to make sure that there are no nil strings in complex types. So this would fail
But this worked
This seemed to work with OS 4.6. Download their beta JDE 4.6 and give it a try.
I spent some time with BB's support last week, and I got the feeling that they weren't going to fix this in their 4.3 and 4.5 releases. So you might be stuck with the workaround (if it works for you) until 4.6.