I am not sure that I understand what you mean by a blank space. Do you want to have few empty categories so that the candlesticks are not plotted to the end of the plot area? If so, you can add few dummy data items in the series items source which have null values. You can check how to define empty data points in the Empty Values demo
Also, if your question is related to RadChartView I would ask you to post it in the corresponding forum section. Note that RadChart is our old charting component which is different than the new RadChartView.
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and share your thoughts.