Sun(light) rotation is not working

Hello, I am trying to set rotation of Sun on the script(game) start. It is based on System.DateTime. All is all right, but rotation is still different(wrong) by my variables.

So here is code:

    var sun : Transform;
    var dayTime : float;	
    if(System.DateTime.Now.Hour >= 5 && System.DateTime.Now.Hour <= 19) //15 hours
    	dayTime = ((System.DateTime.Now.Hour-4)*3600+System.DateTime.Now.Minute*60+System.DateTime.Now.Second);
    	sun.transform.Rotate(dayTime/300, 0, 0);

In game rotation of sun is something like X: 327,Y: 180, Z: 180. But i really dont get it, what is wrong with it? But it have to be something like X: 163, Y: 0, Z: 0. If you want more info, just write what you need. Thanks for answers and help.

Edit: Can it be anything like gimbal lock - Gimbal lock - Wikipedia i really dont know?

Instead of using transform.Rotate, try setting transform.EulerAngles directly with a single Vector3.