Look at not working as expected

This should be an easy one, but i can’t figure out whats going on. I have a plane that gets created in front of my camera. I use look at in the direction of the camera, but the surface faces up instead of at my camera.

var plane:GameObject=new GameObject.CreatePrimitive(PrimitiveType.Plane);
var fwd=viewingCamera.transform.position+viewingCamera.transform.forward*(viewingCamera.farClipPlane-10);
plane.transform.position=fwd;
plane.transform.LookAt(viewingCamera.transform);

The only thing i can think of is that the edge of the plane is facing the camera, not sure why this would be the case.
Thanks in advance!

LookAt will not work in this case, because it points the forward local direction to the target, but the plane normal is the up local direction. You should rotate the up vector to the camera, like this:

...
plane.transform.position=fwd;
var dir = viewingCamera.transfrom.position - plane.transform.position;
plane.transform.rotation = Quaternion.FromToRotation(Vector3.up, dir);;