Incredible victories of Japan ?

[hmsdreadnought]

Hello everybody.
I am a belgian player.
I use the download game, first version (I don't have till download the patch).
I play only standard game (I didn't find the others scenarios).
Game 1 : I lost.
Game 2 to 4, I win.
1 ) Game 5 and the others, I lost... because reaction of AI : I receive now max 8 amphib US group, and Japan 21 !!!
It is no more possible to invade the countries with oil (Java, Leyte...), because no amphib group enough.
Without amphib group, no possible to try to win.
Is it a reaction of IA or a bug ?
2) My 2 last games : with no amphib US group enough, I change my strategy. I attack always by Pacific Central or Samoa or Brisbane to sunk the max of japan carriers. But when Japan had no more carriers, after one turn, the game say that Japan win because he go after 1944 ?? Example : in October 1944, I am ready to recuperate the country with oil, Japan had no carrier, I think : now, I begin to amuse with big campaign… but game say : Japan win !? I don’t understand because during my 5 first games, I play to July 1945 ?
The same when Japan have no carriers in april 1944.
AI accelerate the game when Japan have no more carriers ?
But it is a terrific game and I have much pleasure to play !!!