did you installed it if no go to
www.amxmodx.org/doc/
if yes
enable the fun module it's normally default but
look in \addons\amxmodx\configs\modules.ini and look if this is in it
Code:
; ------------------------------
; Fun - provides extra functions
; ------------------------------
fun_amxx_i386.so
fun_amxx.dll
fun_amxx_amd64.so
NOT
Code:
; ------------------------------
; Fun - provides extra functions
; ------------------------------
;fun_amxx_i386.so
;fun_amxx.dll
;fun_amxx_amd64.so
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