Not getting credit for mission?

Hi,
first, i am a newcomer to Halo 3 so pardon my ignorance. I am in the middle of mission 6 in normal campaign. I noticed that although I got the gamer points and achievements for finishing missions 1 through 4, I did NOT get an achievement for finishing #5. I am not sure why — I resumed solo game each time, as far as I can remember. My questions are (1) what do I do now to get the credit for doing mission 5 — do I play it again from the begining, do I start on mission 4 and redo that too (please say no) or start form a rally point near the end of four? Or something else?

(2) Also, I am almost done with mission six. Do I need to backtrack and get credit for five in order to get credit for six, seven etc? It’s not like I’m JUST playing for the GPs and the little icon, but I don’t want to play through twice just to get the icons, so I wan to nip this in the bud now… Please advise…

Hey, nobody out there can help me on this one???

You need to complete the Campaign levels on Normal or higher for achievements to unlock for completing them.

You don’t need to restart the campaign in order to get credited, go to the Campaign menu and choose the fifth mission and choose Mission Start, not Rally Point Alpha.

That’s what I thought. The thing is, I played through mission five and six and got no credit for them. Then tonight I finished mission 7 and I got credit for it (by credit I mean teh achievement). So I can’t figure out what I did wrong — i did not start mission five or six from a rally point,I just always used “resume solo game”. That’s why I don;t get how this happened – I now have achievements for mission 1,2,3,4,7.