Software :: Mac Trash Cannot Empty Downloads

If I download an app or anything as a matter of fact, I can't delete it. The Trash refuses to empty but I hear the sound it plays when it used to empty normally. This problem occurred when I wanted to set a wireless printer, the printer required downloading an app which I downloaded; and later found useless. I decided to delete it, I moved the app to the Trash and tried to empty it. Finder asked if I want to empty it, I pressed OK, the Trash played the sound but didn't empty. I looked up solutions and one suggested using Terminal; I used Terminal, it worked and emptied the Trash but now if I try to empty anything from Downloads, I can't. The Trash refuses to empty and the whole fiasco begins again.