What the heck is the objective here? help please. i take out all the ground fire then it says go get the tanks, i fly over to help the 169th then it says mission failed.... every time....

this is the second day of this darn level. in the begining the voice over says not to stay on one island too long but if i leave too early then the 172nd get torn up before i can even get to the 169th... AHHHHHHHH

If you dont take out all the planes over the first set of troops when you go to the second (by the time you get there the mission will end in failure) a single bomber will take out the first group. I forget the numbers 171th and 169th...) any who keep going until the bar for that area goes to full. If it is still 1/2 way or less they will be destroyed... Once you have defeted all threats the bar will become full.