Ok, first your borders. They need to be completely re-done following this tutorial. No buts, just follow it. Secondly, your whites are extremely dirty where the trees are and there's still quite a bit of dust in the other whites as well. In every panel. Didn't really check your blacks but from what I can see with out going back into photoshop, they're good. You missed quite a bit of white lines, and there's some black and white lines that need to be stroked.
All of the red boxes are highlighting where there should be white lines, all the blue boxes highlight where a line either needs to be re-stroked, completed or connected.
Note: the blue boxes are for example, except the one that connects the white line. There are way more lines that need stroked than I pointed out. Really, any line that looks broken should be completed and re-stroked.