I discovered something...when the file is named 727_100_5_T (which is be the left wing) there are portions of the wing that do not allow textures to show up.  I realized this during a test when my markings spilled over to the flaps/spoilers.  Only the portion of my markings on those surfaces showed up anything on the silvery top of the wind does not display.  Hoever if you rename the file to 727_100_4_T what you put on the wing is mirrored on both wings.  Is there a hidden layer in the bitmap or is it the model.  This happens to the markings too (exit arrows and APU portal) if you move the to the left or right the portion over the silvery section disappears.   :'(