Red "!" on my custom material in browser

XFunc_CaRteR

L5: Dapper Member
May 14, 2009
248
17
I've made a custom material for a map. It shows up fine in the map, but in the material browser of the texture application tool it's giving me a red box and an exclamation mark ("!"). Anyone know what that means?
 
T

The Asylum

No idea, you can see it on some Valve textures too

If it works, it works, right?
 

Swordz

L5: Dapper Member
Jun 27, 2009
224
37
It happens on some of my custom textures, but it works fine anyway
 

Beetle

L9: Fashionable Member
Aug 17, 2008
627
178
I thought there was a way to make thumbnails of textures - possibly in vtfedit?