With a hotel booking I am getting the message "Unable to retrieve rates for this hotel" for some of the hotels. Some of the hotels were available before but now show this message. I asked one of the hotels directly, they said there is availability for the period I am looking for and the price couldn't be the problem either. I saw another post regarding the same problem that there were some backend memory problems of Concur, so I narrowed down my search till 7 hotels, which is not too much in my view, but still the same problem.

Does anyone know how this can be fixed?