travel reservation from Prague to Poznan

Need help!!! Finally deciphered train schedule from Czech rail for travel on Sept. 26 going from Prague train station to Berlin-Poznan Poland, EC-176 Johannes Brahms Train leaving at 08:21 from Prague then switching to EC-45 Berlin-Warszaw Express at 13:37 in Berlin, but you have to register to purchase a ticket from e store and then you have to try to get a reservation for seat? not guaranteed!!! What kind of service is this, very confusing, is there a bus service to Poznan, I looked on student services the don't have Poland listed, but advertise a Prague to Warszaw trip?, can anybody help me, I am flying in to Prague on Sept 23rd and leave for Poznan on 26th in AM already have all hotels booked.
Thanks a bunch
Ursula

Posted by Laura
Rick Steves' Europe
6008 posts

I recommend buying the ticket when you arrive in Prague. There is a ticket agency at the edge of the old town, which may be more convenient than the train station. For these eastern destinations, buying in person is usually cheaper than using a US ticket agent.