if your using amxmodx and smart ftp find cs/your server ip/port/cstrike/addons/amxmodx/configs/users.ini right click the users.ini file click view delete everything in the file all it should say is
""STEAM_0:0:1551394 "" "abcdefghijklmnopqrstu" "ce"
SAVE THAT SOMEWHERE IN YOUR COMPUTER
and thats the steam id you posted so you can just copy and paste that and put it in there and if you dont know how to uplaod here it is to
right click some where on the white find upload direct then click select go to add files find where you saved your users.ini then click ok it'll upload and it should work
