Requesting value from Server

Hi, I just wrote an event which requests the value from server, but there is always an error , could someone tell me what am I doing wrong? Thx! Here is the Code below:

Client

   TriggerServerEvent("es:getPlayerGangFromIdentifier", -1, function(target)
		     
			 if (target == false) then
			 TriggerEvent("mt:missiontext", "NO", 500)
			 return
			 else
			 TriggerEvent("mt:missiontext", "OK", 500)
			 end
	end) 

Here’s the Server Side

RegisterServerEvent("es:getPlayerGangFromIdentifier")
AddEventHandler("es:getPlayerGangFromIdentifier", function(identifier, cb)
    local identifier = GetPlayerIdentifiers(source)[1]

	local executed_query = MySQL:executeQuery("SELECT * FROM users WHERE identifier = '@name'", {['@name'] = identifier})
	local result = MySQL:getResults(executed_query, {'permission_level', 'money', 'identifier', 'occupation'}, "identifier")
                
                local getModel = result[1]
                 
	if(getModel['occupation'] == "mafia" or getModel['occupation'] == "twgang")then
		cb(true)
	else
		cb(false)
	end
end)

Thank you!