Correct type convesrion

placesquare = function (spot)
    spot = tonumber(spot)
    if spot_availability[spot] >= "0" and spot_availability[spot] <= "4" then
        spot[spot] = display.newImageRect( "spotsquare.png",25,25)
    elseif spot_availability[spot] == "6" then
        spot[spot] = display.newImageRect("nothing_spot.png",25,25)
    elseif spot_availability[spot] == "7" then
        spot[spot] = display.newImageRect("1_coin_spot_blue.png",25,25)
    elseif spot_availability[spot] == "8" then
        spot[spot] = display.newImageRect("2_coin_spot_red.png",25,25)
    end
    return 0
end

    placesquare(spot[6])
    spot[6].anchorX=0
    spot[6].anchorY=0
    spot[6].x=125
    spot[6].y=10
    spot[6].alpha=0.4
    group:insert(spot[6])