UnityScript ScriptableObject error

In C# it’s a piece of cake to create instance of ScriptableObject. I try to do the same with UnityScript.

//MyMonoBehaviorClass.js
var mScriptableObject = ScriptableObject.CreateInstance(typeof(MyScriptableObjectClass));
mScriptableObject.foo();

//=================================================================
//MyScriptableObjectClass.js
class MyScriptableObjectClass extends ScriptableObject
{
    function foo()
    {
        print("Hello from foo()!");
    }
}

I get error: “ScriptableObject.CreateInstanceFromType can only be called from the main thread.” What’s wrong?

#pragma strict
var mScriptableObjectClass : ScriptableObjectClass;
function Awake()
{
mScriptableObjectClass = ScriptableObject.CreateInstance(typeof(ScriptableObjectClass));
}
function Start()
{
mScriptableObjectClass.foo();
}