Ok, perhaps Izzy (ragecgi) or anyone else can correct me if i get something wrong but...
AE is not a 3D program, it's only a 2.5D program (which i think means you aren't actually in true 3D space, but things can kind of be moved around in 3D)
AE is not going understand anything from the ma file other than camera data and locator positions
i've seen Izzy do it before...
for something to show up in the composition you need to have a camera that wasn't your default perspective camera. if you've animated your perspective camera (BAD IDEA) then you should duplicate it and parent it to the perspective camera. then go edit > keys > bake simulation >  and reset the options.
you also need to rename locators with a "null_" prefix or they wont show up in AE
export as maya ascii
basically what you can do now is in AE is import that .ma watch the camear as it moves around the locators (now shown as mega huge null objects)
change the null shapes scale to something like 2% if you want to see them about the same size as you did in maya
so now you can replace the null shapes with objects you have in the project files by alt dragging them onto the null shape layers in the comp
you still have to render stuff out from maya, you can't just bring in models and work with them in 3D in AE.
in short, merik is correct
only camera and locator data can be brought in
that's a "Ch" pronounced as a "K"
Computer skills I should have:
Maya, XSI, Photoshop, AfterEffects, Motion, Illustrator, Flash, Swift3D