iOS + Unity and issues with the accelerometer

Hi, I'm trying to tell which way the iPhone is tilted in the left landscape mode - either right or either left. For that, I'm using the Unity tutorial on how to work with the accelerometer: http://docs.unity3d.com/Documentation/Manual/Input.html (It's at the bottom). However, it's almost impossible to differentiate between the x and z result. If I go left, they both turn negative, if I go right, they both turn negative again. Am I doing something wrong or is there a better way to tell if it's tilted left/right? Thanks.