stratety doesn't work.

[zhaofang8898]

if the high[0] is the highest of the loast 30 period, generate a down arrow.

[NinjaTrader_Bertrand]

Are you working this out in the Strategy Wizard? If so please post a screenshot of your setup conditions, you might want to do something like this

if (CrossBelow(High, MAX(High, 30), 1))
{
DrawArrowDown("Sell" + CurrentBar, false, 0, High[0] + 1 * TickSize, Color.Red);
}

[roonius]

if the high[0] is the highest of the loast 30 period, generate a down arrow.

if(High[0] == MAX(High, 30)[0])
// Do your stuff

or

if(HighestBar(High, 30) == 0)
//Do your stuff

[zhaofang8898]

if(High[0] == HighestBar(High, 30))

[NinjaTrader_Josh]

zhaofang8898,

Please do not mix and match the concepts. Roonius provided you with two separate ideas that will do what you have specified. You can either go with option A or option B.

[zhaofang8898]

thanks a lot for your help, guys