The travellers may be confused by time zone.

They planned to arrive in there, for example, Sept 14, but one day earlier than the date, because booking the hotel with China time (zone). There is a time difference between China and Sweden though. So, they arrived in the hotel earlier. Unfortunately, there was no room available for them. Under such situation is not uncommon. The hotel and the travellers could readily resolve the problem, if a sufficient communication was done. 

A lesson is learned for them or others before a travel that requires a good plan.