When I open Agreements, Tax, and Banking in iTunes Connect, I see the message:
"Our records indicate that your banking information is incomplete. Please access your banking information and update as necessary."
So, I follow this recommendation and go to Bank Info > Edit > View/Edit Existing Bank Account > Edit Bank Account Info
Then I see a new field named UNN. Quick help says: "Enter the nine-digit UNN for your account."
What is this? Google can't answer this question as well as bank support.
P.S. I've added a screenshot to my post, but HTML images doesn't work, so here is the link: http://i.imgur.com/p9PuJME.png