'MouseLook.sensitivityX' is inaccessible due to its protection level.

I'm getting this error when trying to create a slider GUI to adjust mouse sensitivity while in game? I know the script is correct for accessing the MouseLook Script and variable, but I'm still getting the error:

'MouseLook.sensitivityX' is inaccessible due to its protection level.

any Ideas?

//Look Sensitivity x axis
    GUI.Label(Rect(25,125,100,150),"X Axis");
    MouseLook.sensitivityX = GUI.HorizontalSlider(Rect(25,150,100,25),MouseLook.sensitivityX, 2.0,15.0);

If it is talking about protection level, then presumably the variable is not "public", e.g.

public static float sensitivityX;

public static var sensitivityX : float;

You can't just call the sensitivityX property of your script, that's not how the scripting works.

You need to get a reference to the MouseLook script before you can change it. Like this:

// C#
MouseLook ml = GetComponent(typeof(MouseLook)) as MouseLook;
ml.sensitivityX = 1; // or whatever