* In backtesting Backtesting the signal is calculated on Close price of the main series and Multicharts "thinks" that prices between OHLC exist.
* In Data Playback mode the signal is calculated on Close of the main series and MC tries to execute orders on OHLC prices of the detailed data series and MC "thinks" that prices between OHLC do not exist (how detailed your data series is depends on the selected data playback resolution).