I tried to convert this free indicator and my current code is below.
Zorro says that "Error in 'line 22:
'FextMapBuffer6' undeclared identifier".

Why this happen?
Thanks in advance.

The original indicator.
http://www.pointzero-trading.com/FreeMetatraderDownloads/view/5

Code:
function run(){
	
 
int    FastEMA             = 9;
int    SlowEMA             = 26;
int    AvPeriod            = 400;
var    Gamma               = 0.75;


vars med = series(MedPrice());

vars median = series(MACD(med,FastEMA,SlowEMA,4));
vars FextMapBuffer6 = series(median[0] - median[1]);
vars FextMapBuffer5 = series(abs(FextMapBuffer6[0]));

var flat = EMA(FextMapBuffer5,AvPeriod);
vars FextMapBuffer3 = series((flat * Gamma));
vars FextMapBuffer4 = series(0 - (flat * Gamma));
}

if(FextMapBuffer6 > FextMapBuffer3)
exitShort();
enterLong();

if(FextMapBuffer6 < FextMapBuffer4)
exitLong();
enterShort();
}