Need help adding music...

I've read the wiki, but when I try to add music to my wad, it doesn't play. I'm trying to replace O_MAP14M, and I named my .mp3 correctly. When I go to my map it still plays the vanilla O_MAP14M even though I have my music lmp added.

What am I doing wrong here?

(Before someone says it, I know I should convert it to OGG for a lower file size, but the wiki says it should play .mp3s. I'm just worried about getting my music to play.)

EDIT: Ah, I meant to put this in editing help. I shouldn't post at one in the morning.

http://wiki.srb2.org/wiki/Music_slots
The following tells you which Music Slots are in use and which aren't. Slots 1-32 are in use. 33-39 aren't. So I recommend instead of replacing a Music Slot already in use, find a music slot that isn't in use and insert your music there.

Here is how to add music the simple way(well simple in my opinion, however there could be easier ways):
1.Make a new wad. Name it according to the music slot your using(Note you don't have to do it that way however it is easier to remember). So for example, if you were using music slot 33 name the wad Map33.wad.
2.Create a new lump according to the Music Slot you are using. Since we are using slot 33 make the lump like this:O_MAP33M.
3.Right click the newly created lump. This will show you a set of options. Click on the one that says Import. After doing so find the folder your song is located in and click on it.
4. Once thats done save your wad. Add your wad onto Srb2(The wad,in this case, is called Map33.wad). Now in order to check if you successfully added your music wad you're going to type a command to see if it worked or not.
5.The 'tunes' command specifies which levels' music you want to hear. For example if you want to hear GFZ1 music enter 'tunes 1' and that song will play. We added a wad named Map33. There is no actual map there only the music. So we are going to enter 'tunes 33' to play the music that is on Music Slot 33. If you hear your music then you succeeded. If you don't hear anything then come back and I'll clarify things some more.

Note: Slots 33-39 are not the only unused music slots. There are many more that are unused. Just check the list to see which are and which aren't.

Honestly, that's pretty much exactly what I did, but it wouldn't work for me. When I did it that time though, it worked for some reason.

So thanks, man! I don't really know what went wrong the first time, but who cares