Encountered and error D':

just wondering if anyone here can tell me what this error is. i have just bought a second server and installed PropHunt and this error came up out of the blue and i have no idea how it is causing it and what making this error. Pls save my soul from this error xD

[color=rgba(255, 255, 255, 0.7)][ERROR] gamemodes/prophunt/gamemode/cl_init.lua:102: attempt to call method 'InitPostEntity' (a nil value)
1. unknown - gamemodes/prophunt/gamemode/cl_init.lua:102[/color]