I'm not the autor of this script. The original ZoneTrade script http://codebase.mql4.com/4797 is developed by the Duke3D. The Heiken Ashi version of the ZoneTrade script is developed by the brother3th. Thanks to the autors of their work.
Accoding to the developer of the ZoneTrade indicator it is working in this way:
If the current bars of AC and AO are green, it shows that the zone is green.
If the current bars of АС and АО red, it shows that the zone is red.
If the bars of AC and AO are differently directed then the bar is colored grey (grey zone).
Sorry people how do you set up this indcator on meta trader 4? i seem to have problems on it.basaically it comes up but its the same as the usual candle sticks the grey candles dnt show up.i know the trade zone trade iam just not sure how to set this up on mt4.