M Effect 2 Question?

Kk i was doing the loyalty missions for the first set of squad members i recruited before i recruit the next 4. i did jacks loyalty mission first and i just completed mirandas mission and at the end i had to choose between the 2 and i chose miranda, now jack isnt loyal for some reason. how do i get her to b loyal again cuz im goin for the achievement that requires every1 to survive the final mission.