Shoutbox

@Kally

There are two different places to view your sounds:
One is your local sound library (Contact List > Plus! > Sound Library). All your installed sounds will be listed there.

Another place is the panel which you can bring up in a conversation window. But this panel will only show the sounds which you have listed as "visible" in your local sound library. You can still also use the invisible sounds though, although they wont be listed in this panel.

If you notice, in the local sound library there is a column (the 3rd one) which shows if a sound is visible ("show") or not ("hide") in the sound panel in a conversation window. Make sure your new sounds are listed as visible ("Show")...

A related option to this is:
To automatically show every new sound you recieve from a contact in the custom sound panel in a conversation you need to enable the option: Contact List > Plus! > Preferences > General Options > Sounds > Show newly recieved sounds in the sound panel by default
Note that imported sounds from a soundpack are always visible by default.