[amibroker] How can I backtest an index like the DJI?

["professor77747" <professor@xxxxxxxxxxxxxx>]

Every time I run a backtest on a database containing an index, I never 
get any buy or sell results for the index. If I run a backtest on the 
index only, I still do not get any results. However, I know that my 
formula would trigger buy and sell signals. Why wouldn't the backtest 
work on an index. I have used ^dji and indu-nyse-ind as symbols.
What is wrong?

Thanks
Tom