if all the servo's are working properly maybe a linkage is not connected properly, or maybe the movement is going into the flybar or something. If the heli is not spinning and you change the collective, sometimes it will only change the pitch of one blade, but it will also change the flybar as well. It's really not about being stationary and moving stationary parts, it's the relation of all the moving parts together if that helps.

If your heli has the hiller head and not the bell hiller head, then changing the collective really has nothing to do with directly changing the pitch. Actually the flybar spinning and the resistance for it to move out of it's flat plane will pitch the blades, so basically if the head is not spinning it might not work as you think it would.

If all 3 servo's are moving up and down together when you move the collective, and all the linkages are good to go, give it a small spin up test and check the tracking and all of that. If one blade is not pitching, it will give you a really bad wobble.

If you feel like there might still be a problem, take some pics of your heli, especially the head and linkages and post them, and we can tell you if it's setup right =)