The NC Mall is currently undergoing some sort of issues with loading, purchasing Neocash, buying items, opening capsules and trading items.
I haven't heard an ETA on a fix
Make sure you are copying this part of the URL specifically
http://www.neopets.com/music.phtml?secretavatar=632e80e14404fad9
If you have the premium portal on, try turning it off to see if it helps you recognize your unique URL more clearly.