help pliz

[Jacobob14]

iwant to know the exp is needed in the next level but it gives me error

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    function lev(player) 
        local level = exports.exp_system:getPlayerLevel ( player ) 
        local name, expreq = exports.exp_system:getLevelData ( level ) 
        local name1, expreq1 = exports.exp_system:getLevelData ( level+1 ) 
        outputChatBox ( name ..": ".. expreq.." - "..expreq1, player ) 
        setElementData(player,"expreq",expreq) 
        setElementData(player,"expreq1",expreq1) 
    end 
addEventHandler ( "onPlayerJoin", getRootElement(), lev ) 
addEventHandler ( "onPlayerLogin", getRootElement(), lev )