You a paying your broker to execute trades for you. If for any reason that is beyond their capacity to do so, for any stock you hold or care to hold, they are legally obligated to explain the reason(s) that prohibited that trade's execution, in a way so you are able to understand. In some cases it may be the particular broker's rules on particular order types or particular listing platforms, but a "trading halt" appearing on your screen when attempting to place an order, should not be an indication of that type of situation.
Personally I would call or e-mail my broker and demand a specific and satisfactory answer, because executing trades for me when I choose to do so, is in fact what I am almost exclusively paying them to do for me.
Good luck, and I hope you care enough to pursue an answer, because a change in a stock's listing platform due to listing eligibility requirements, is one of the reasons a halt can be issued. Since TADF's 2012 10K report is now over a year past it's extended due date, they could be moving onto the grey market any day. If that happens to be the case, that would be very helpful information for any current holders to know.
I bailed on TADF over a year ago, so I am only curious myself, but if I were holding, seeing a trading halt would need a swift answering for.
