I have just tried to script an editor script, and it just shows "multi-object editing not supported," and nothing else. the script:

#pragma strict

@CustomEditor(PlayerController) @CanEditMultipleObjects

class PlayerEditor extends Editor{

var Speed: float = 0.0;
var SProp: SerializedProperty;

function OnEnable(){
    SProp = serializedObject.FindProperty("MSpeed");
}

function OnInspectorGUI(){
    serializedObject.Update();
    Speed = EditorGUILayout.Slider(Speed, 1, 150);
    if(!SProp.hasMultipleDifferentValues){
       PBar(SProp / 100.0, Speed);
    }

}

function PBar(val: float, label: String){
    var rect: Rect = GUILayoutUtility.GetRect(18, 18, "Text Field");
    EditorGUI.ProgressBar(rect, val, label);
    EditorGUILayout.Space();
}

}

is here. any help would be much appreciated. thanks in advance