A little background. I am using AMIBROKER version 6.20.1 64 bit on a Windows 10 pc.
The problem exists in Backtest, Exploration and Scan modes. It seems independent of what afl is being used. To get to the problem I first go to File/Open Database and select the US premium data set. Next open up an afl formula file and send it to the Analysis Window. In doing that I note that the ticker symbol box at the top of the window graciously shows I now have access to a massive list of ticker symbols. But I only want an analysis that uses a portion of the available tickers. I made a simple watch of only 5 ticker symbols. I then used the apply filter tool to select my watch list. Running the analysis produces an error message which states "Notice No signals matched Apply to........". In other words the matching process of filtering the many tickers down to a smaller number is not happening. The same thing happens when I use any of the built in watch lists.
I must be missing something simple.