Cylinder Problem - Black Texture

In my HL2EP2 map, I am trying to make a sewer using a half of a cylinder (screenshot below) but it is giving me these black textures on some of the surfaces. In this screenshot I pointed a flashlight at each of those textures (for the one's wondering how I kept the light of the flashlight there, just type "create_flashlight" in the console)

[IMG]http://i45.tinypic.com/2aj16v8.jpg[/IMG]

To avoid confusion, The wall in front of me doesn't have the bug, that is just some bad light placement of mine.

Niborius said:
In my HL2EP2 map, I am trying to make a sewer using a half of a cylinder (screenshot below) but it is giving me these black textures on some of the surfaces. In this screenshot I pointed a flashlight at each of those textures (for the one's wondering how I kept the light of the flashlight there, just type "create_flashlight" in the console)

[IMG]http://i45.tinypic.com/2aj16v8.jpg[/IMG]

To avoid confusion, The wall in front of me doesn't have the bug, that is just some bad light placement of mine.

Edit: Making the cylinders a func_detail fixed the issue.

Edit 2: ^ that was an edit fail.