[@Rog2548] and @[bhagya3udana856] 

You have to round to the nearest 1000. you can BUY/SELL 1000, 2000 but not 1500

(int)(1000*Math.Floor(Position.Volume*2.5/1000))

@didpenny

The right approach is below. its something @tmc. needs to correct

renko = Indicators.GetIndicator<Renko>(RenkoPips, BricksToShow, 3, "SeaGreen", "Tomato");