GMPublish vmt and vtf file list verification failed

[TRGraphix]

Error Code:
Executing queue.
Creating addon from C:\Users\Georg\Desktop\christmasgun...
Creating temporary addon.json.
Converting filenames to lowercase...
Done!
Creating temporary gma.
Garry's Mod Addon Creator 1.1
Looking in folder "C:/Users/Georg/Desktop/christmasgun/"
 lua/weapons/ttt_christmasgun.lua
 materials/icon/swep_icon.png
 materials/models/unconid/xmas/snowman_u.vmt
 materials/models/unconid/xmas/snowman_u.vtf
 materials/models/unconid/xmas/snowman_u_normal.vtf
 materials/models/unconid/xmas/tree_xmas.vmt
 materials/models/unconid/xmas/tree_xmas.vtf
 models/unconid/xmas/snowman_u.dx90.vtx
 models/unconid/xmas/snowman_u.mdl
 models/unconid/xmas/snowman_u.phy
 models/unconid/xmas/snowman_u.vvd
 models/unconid/xmas/xmas_tree.dx90.vtx
 models/unconid/xmas/xmas_tree.mdl
 models/unconid/xmas/xmas_tree.phy
 models/unconid/xmas/xmas_tree.vvd
 vgui/ttt/swep_icon.vmt
  [Not allowed by whitelist]
 vgui/ttt/swep_icon.vtf
  [Not allowed by whitelist]
File list verification failed
Creation OK!
Finished running queue.
Refreshing addon list.
Retreving list of Addons.
----------------------------------------------------------
Can someone tell me why?