What's wrong with RectTransformUtility.RectangleContainsScreenPoint Camera argument?

Hello! I am trying to use RectTransformUtility.RectangleContainsScreenPoint but I have weird trouble with camera. I just have empty project with new scene which have camera on it, also it have UI panel and canvas, so it should be not any conflicts. But finnaly I have this problem Debug.Log(RectTransformUtility.RectangleContainsScreenPoint doesnt work if CAM parameter will be not null. I mean:

RectTransformUtility.RectangleContainsScreenPoint (rect, pos, Camera.main) - doesnt work

public...

What's wrong with RectTransformUtility.RectangleContainsScreenPoint Camera argument?