Click on the latch. Or, whatever key combination you have assigned for door 2 (e.g. shift-E + 2). 

You may have been doing it right but this is a bug that haunts many flight sim aircraft. For some reason somtimes the key-combination keystrokes will fail to open the selected door or window and just open the first window. For example I have the key "e" to open the crew door and then e+2 e+3 e+4 etc for the rest, and sometimes no matter which number I press after pressing the "e" button the first one will always open (the crew door).  Sometimes this is not the case and I've been told by other folks that it's a gauge conflict or something like that. Luckily on the C-130 there are clickable areas that allow you to open the doors which always work.

JC