Sky Stream Aktivierungsproblem

Hello everyone,

My StreamBox cannot be connected to my account.

A message appears on the TV asking me to activate my Sky account under "sky.de stream activation." As soon as I enter the one-time code displayed on the TV, I receive the following error message in the browser on my PC and smartphone. 

Siebel_Business and generic error

Does anyone have any idea what could be causing this?