[amibroker] if (Buy[i] >= 0) not behaving as expected

[gmorlosky]

In the line ~9 "if(Buy[i] >= 0", if I change that to 1, which is equal to a 
Buy, I get no Plots, even though the Explore shows 1s for half the tickers, 
else with 0, I get all plots. What is wrong ?

NumBars = 20;
fvb = Status("firstvisiblebar");
for( i = 0; ( symbol = StrExtract( TickerList, i ) ) != ""; i++ )
{
Buy = IIf(ROCt > ROCc AND RSIt > RSIc, 1,0);
Sell = IIf(ROCt < ROCc AND RSIt < RSIc, -1,0);

fc = Foreign( symbol, "C" );
if (Buy[i] >= 0) // something not right here ???
 {      
  if( ! IsNull( fc[ 0 ] ) )
  {
    Plot( 100 * ( fc - fc[ fvb ] )/ fc[ fvb ], symbol, colorLightOrange + ( 
(2*i) % 15 ), styleLine );
  }
 }
}