360 Controller and angle problem

Hi everybody!

It's the first time I need help to a problem i cannot resolve. I try to use the Xbox 360 controller to test severals controls, and there is one who resist to me !

In a XY world who use Z for depth, i didn't succed to make a simple 2D rotation (Z rotation exactly) with an angle.

I don't know if it's my formula who are wrong, i try differents things...

Here an example of what i want to do !

There is the code i use to make something who didn't work :

 float fltx = transform.position.x + xbContrl.state.ThumbSticks.Left.X;
 float flty = transform.position.y + xbContrl.state.ThumbSticks.Left.Y;
 float fltz = 0.0f;
 
 Vector3 vt3To = new Vector3(fltx,flty,fltz);
 Vector3 relativePos = vt3To - transform.position;
 Quaternion rotation = Quaternion.LookRotation(relativePos);
 transform.rotation = rotation;

In fact, the angle work but it's not the correct face of my object who are in front of this angle.

Nota : I used 2D Toolkit to make a sprite and rotate him. And the XInput : http://speps.fr/xinputdotnet