Trying to extract data from iCustom into EA

Hi, I could use some advise here. I am writing my first EA here and have come across a stumbling block. I want to use data from an indicator called Slope Direction Line. Basically, I want to use whether or not the slope is up or down.

Here are the buffers and inputs:

 //---- input parameters 
extern int       period=80; 

extern int       method=3;                         // MODE_SMA 

extern int       price=0;                          // PRICE_CLOSE 

{ 

    IndicatorBuffers(3);  

    SetIndexBuffer(0, Uptrend); 

    //ArraySetAsSeries(Uptrend, true); 

    SetIndexBuffer(1, Dntrend); 

    //ArraySetAsSeries(Dntrend, true); 

    SetIndexBuffer(2, ExtMapBuffer); 

    ArraySetAsSeries(ExtMapBuffer, true); 

    

    SetIndexStyle(0,DRAW_LINE,STYLE_SOLID,2);

    SetIndexStyle(1,DRAW_LINE,STYLE_SOLID,2);

    

    IndicatorShortName("Slope Direction Line("+period+")"); 

    return(0); 

} 

I want  to pass on whether or not the line is in a downtrend. So I am using Buffer 1 as a boolean:

 bool dn1 = iCustom(NULL,PERIOD_D1,"Slope Direction Line",80,30,0,1,0);

The problem is that this value always returns false, no matter what the real value is. I included an alert to show the value and it's always true, even when the indicator shows an uptrend. Obviously I am interpreting something incorrectly. Any ideas? Thank you.