[amibroker] Help on why IIF statement isn't working ?

[gmorlosky]

I have this code and the middle line of the "IIF" statement keeps telling me 
it's the wrong argument ?

function GetSymbols()
{
 TickerList = "";
 SymbolList = CategoryGetSymbols(TickerCategory, TickerListNum);

 for(n = 0; n < NumTickers; n++)
        {
         Ticker = StrExtract(SymbolList,n);
IIf (InWatchListName( "1_S&P 1500 N100" ), Ticker = Ticker, Ticker = "");
         TickerList = TickerList + Ticker + ",";
        }
 return TickerList;
}