Backspace doen't work with Listary 4 on Win7

I’ve just upgrade to Listary 4 (free) and the backspace doesn’t work anymore :(. After typed some character to find, I hit the “backspace” key to correct my typo, but it doesn’t work, mean that nothing happen, the sentence in Listary text box are NOT deleted, and the Window Explorer stay on the current folder.
Please show me where I can find the option to check (or to show you my settings). I’ve just install, didn’t config anything.

This sounds really weird. There is no option related to this behavior. Is it possible that backspace is blocked by other applications/Explorer plugins/shell extensions?