Triangle Brush Error

[-Psy-]

Placing detail props : 0...1...2...3...4...5...6...7...8...9...Material NATURE/BLENDGRASSGRAVEL001A uses unknown detail object type coastline_redgrass02!
Material NATURE/BLENDGRASSGRAVEL001A uses unknown detail object type coastline_redgrass02!
Material NATURE/BLENDGRASSGRAVEL001A uses unknown detail object type coastline_redgrass02!
Material NATURE/BLENDGRASSGRAVEL001A uses unknown detail object type coastline_redgrass02!
Material NATURE/BLENDGRASSGRAVEL001B uses unknown detail object type coastline_redgrass03!
Material NATURE/BLENDDIRTDIRT001A uses unknown detail object type citygrass01!
Material NATURE/BLENDDIRTDIRT001A uses unknown detail object type citygrass01!
Material NATURE/BLENDDIRTDIRT001A uses unknown detail object type citygrass01!
Material NATURE/BLENDDIRTDIRT001A uses unknown detail object type citygrass01!
10
Compacting texture/material tables...
Reduced 2944 texinfos to 2192
Reduced 231 texdatas to 217 (9236 bytes to 7957)
Writing C:\Program Files\Valve\Steam\SteamApps\psychofreak001\sourcesdk_content\cstrike\mapsrc\cs_industrial.bsp
23 seconds elapsed
  1.049162 -3.207047 0.000000
  -1.049033 -3.207047 0.000000
  -1.049033 3.206336 0.000000
  1.015345 -3.207047 0.000000
make_triangles:calc_triangle_representation: Cannot convert
Memory leak: mempool blocks left in memory: 17

For some reason, this error keeps appearing! I go to the co-ordinates and find nothing there =/ How can I solve this?

(And what is this Material error all about?)