Lua error when changing gamemode Garry's Mod

[DubKing]

hello, everytime i try to change gamemode on my server on Garry's Mod it gives a lua error


this is my console:


as i read it it says that the file is not there while it actually is.


i have 8Gb ddr3 memory
i have a i7-3612QM CPU of 2.10GHz

i know the server works because i had a few friends to join it
here is it while playing sandbox

everything works as it's supposed to when the gamemode isn't changed
but stays at sandbox
there are no admin mods yet