What did you enter in the search field?
In search field i enter: "mc", "firefox", "fluff", ...
mc.tcz found in frame "Select Extention". If select mc.tcz and click "Go", Midnight Commander begins to download, install, and works well. Other programs too.
But if i enter "mc.tcz" in search field and press Enter, frame "Select Extention" clear and then need click "Connect" to show tcz list again.