game ends August 1941, 11 turn

[slapenkopf]

i am playing Barbarossa and the date in the game is 9th August 1941 and the game has ended. I lost playing as Germany. It the 11th turn and i have taken Leningrad, Moscow is surrounded. (1 unit in Moscow and a officer unit) I have totally surrounded all the Russian divisions in the center. i think the is 11 units outside the encirclement. in the north there is max 6 units left. The south i am struggling a bit, but getting control. have i done to well that the game ends at the end of turn 11. I had a minor loss, if i had 10 more turn i would destroy Russia. why has it done this