Did you press and hold the Tivo and that other button down until the remote light turns on? Then, you can press the code and then ENTER (not select).
Original S1 (Recycle Heaven)
Series 2 (PLS, sold)
TiVo HD (XL, PLS, "652")
Juliet Basic (4XL, PLS)
The TiVo Apocalypse begins on Sat 2013 Feb 16 00:00 GMT!