I am retexturing de_dust2 and I'm having a bit of a problem with my skybox. I think that's what the problem is. When I look one way, the sky works fine, but then when I look at a certain angle, the sky disappears and the textures bleed into the area that the sky should be. What causes this to happen?

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=105660717