function CheckUserInDB bringt mir errors

function CheckUserInDB (pname,label)
	local sql = mysql_query(handler,"SELECT * FROM `players` WHERE `Username` = '"..pname.."'")
	if sql then
		local run = mysql_num_rows(sql)
		if run == 1 then
			--Wenn es den User gibt
		elseif run == 0 then
			guiSetText(label,"Diesen User gibt es nicht!")
		end
		mysql_free_result(sql)
	else
		outputServerLog("Mysql Error: "..mysql_errno(handler))
	end
end
addEvent("checkPlayerInDB",true)
addEventHandler("checkPlayerInDB",getRootElement(),checkPlayerInDB)