xbox 360 achievements issue

[Terrin 1]

Hi I was wondering about 3 achievements on the xbox version most people think they are bugged I was just wondering if they have to be met a certain way if you could help that would be great 2 of them are

Revenge Is Sweet 75 gamerscore

Execute Dr. Mao Shin

Titanic 20 gamerscore

Sink the enemy Carrier

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the 3rd achievement is

Fence Off 10 gamerscore

Defeat the enemy Carrier in naval combat