Why does my promotional code system not work?

plrData[Plr]["Codes"] = {}
Events.EC.OnServerEvent:Connect(function(Plr, Data)
    if Data ~= nil or Data ~= "" then
        local codeToEnter = string.upper(Data)
        for i, v in pairs (plrData[Plr]["Codes"]) do
            if v == codeToEnter then
                print("FOUND") -- code matched, it is definitely there
            end
        end
        if plrData[Plr]["Codes"][codeToEnter] then
            print("code found, unsuccessful")
        elseif not plrData[Plr]["Codes"][codeToEnter] then
            print("new code, engage benefits")
            table.insert(plrData[Plr]["Codes"], codeToEnter)
        end
    end
end)

"Data" is just what the player has inputted and fired an event with this information, but despite being in the table 100% using my sanity check measure, this script still thinks the code does not exist within the table, does plrData[Plr]["Codes"][codeToEnter] not actually check to see if the code exists?