Two of four RCS thrusters don't work

[CanOmer]

I hardly managed to dock in Kerbin's orbit for the first time because two of four RCS thrusters don't work on the smaller craft. What can be the problem?

[CanOmer]

How can I pass approval by moderator?

[sal_vager]

13 minutes ago, CanOmer said:

How can I pass approval by moderator?

It's easy, reach three posts without turning out to be a spambot

After that you're fine, welcome to the forums!

[Alshain]

There is a bug (or possibly a 'feature') where RCS thrusters attached to a service bay will be considered inside the service bay and will not function.  Thanks to the gizmos, I can't tell for certain where those RCS thrusters are attached as you could have attached them to the service bay and then slid them down with the gizmo.  So, try this.  Open the service bay, fire the thrusters.  Let me know if it works.

[Hotaru]

It's kind of hard to tell from the picture--is that a service bay right under the capsule? If so, it's possible that's the problem: service bays can cause issues with engines or thrusters placed near them. Basically, KSP isn't very good at figuring out what is and isn't inside the bay, so some of your thrusters might be registering (incorrectly, obviously) as "stowed" in the bay and therefore not working. If this is the case, try a setup with the RCS further away from the service bay.

[Death Engineering]

As @Hotaru mentioned, service bay occlusion extends to parts not attached or "stowed" (bug).  It may look weird, but you can also just open the service bay and they'll enable. Same for chutes that complain they can't deploy while stowed. 

[CanOmer]

They worked after I open service bay, thanks. Here a close look:

They are symmetrical, so I didn't think service bay can cause a problem. If thrusters on the right work why not left thrusters..

Edited January 10, 2016 by CanOmer

[Markarian421]

I've been having similar problems in 1.0.5 -- RCS and parachutes anywhere on a vessel that has service bay may or may not work seemingly at random unless the service bay is open.  It's sometimes a little tragic when only too late you see only one of your four parachutes will open and your ship is now headed at the ground too fast and sideways . . .

[Death Engineering]

This bug has been present since we saw service bays so I'm a little surprised it lives, but the only way I know to fix is make sure chutes/RCS thrusters are at least two linear parts away from the service bays.

[Alshain]

3 hours ago, CanOmer said:

They worked after I open service bay, thanks. Here a close look:

They are symmetrical, so I didn't think service bay can cause a problem. If thrusters on the right work why not left thrusters..

Lol, don't try to find logical explanations for bugs, unless you are programming a fix.  It will drive you to madness.

In your case you can easily move the RCS to the fuel tanks in symmetry.  You will have to place 2 pair, but it will work just fine.