All okay now
Thanks for the reply. Today it is all working as it should. It appeared to me that something was 'down' or 'unavailable', hence the Error:400.
I installed CS5 upgrade and re-installed all my extensions. I had activated Form Builder on day 1. As far as I know, nothing else had changed here. Day 2, I couldn't activate any WA extensions, but on Day 3 all is good ??
Whatever the case, I am okay now. Thanks