Missing Stocks

I keep typing in stocks and getting a message that they are not available. The stocks are available and one of them you recommend.   I just got an email about BKTI moving to your A list, but then when I type in the ticker to research it, I get the message"   Stock BKTI does not exist or its data is not available.    This is very frustrating.   This is occuring with several stock tickers that are in your database which are available on the "comparison" tab, but not from the main screen.