I have the same problem. I booked through seat24.de and got a 6-digit booking code and also a e-ticket number (781...). I can choose a seat at seat24.de, but they charge additional money for this "service" ( ~20$). I cannot find my booking with either the 6-digit booking code nor the e-ticket number at the China Eastern website. I get the message "data extraction failed" when entering my data and searching for the booking.