The delete and archive buttons work only if a message row is selected.
Could you tell me a bit more about this? It works fine for me; I tried with FF27 and IE11 too. Does anything at all happen when you try and use the delete option? Are there any JS errors or anything like that?
Sorry for the noise. Your plugin works on a plain Roundcube installation. It must me one of the other plugins which prevents delete/archive commands from execution if no row is selected.