Game Sparks Real Time Multiplayer

Hi, i trying to implement the realtime multiplayer in my game, but following the tutorial:

https://docs.gamesparks.com/tutorials/real-time-services/corona-real-time-guide.html#

local function send() local data = gs.getRTData().new() --Set Number data:setLong(1, varLong) --Set Vector data:setRTVector(2, varVector) --Set Float data:setFloat(33, varFloat) --Set Double data:setDouble(56, varDouble) --Set String data:setString(78, varString) --set nested data object data:setData(90, varData) mySession.session:sendRTData(1, gsrt.deliveryIntent.RELIABLE, data, {}) end

i have an error on creating RT Data object:

gs.getRTData().new()

gives me error of "attempt to call field ‘getRTData’ (a nil value)

i don’t know why?