Thanks mpdeveloper_B, it is defined as a panel, I tried to turn it to entity and it worked, the entity-interface displayed correctly.

But I want to re-use the Sphere's menu, which is defined as panel, the (turning gray) TGA panel will be used as the sphere's menu background, so to make them stick together well I have to use panel instead of entity.

Does anyone have the same problem and how to solve this turn gray bug? Please help me!

And I have another question ^^, if you did it and have some code that make a panel always be at the center of the screen (even if the player change resolution) please show me. Thank you!