playing mp3 when i join my server ( not working)

[NeXt]

when i join my server... i hear... ''welcome to the server''... but i wanna change it to a mp3 file. I tryed a lot of things.

tis is my actionsoundlist.txt

//
// actionsoundlist.txt
//
// Place all your action sounds in this file
//
// This file uses aliases to define
// the sound name, they must not be altered !!!
//
// The second part on each line is the location
// and name of the file itself. You can change
// this to be wherever you want.
//
// In the example below I have commented out
// joinserver, roundstart and roundend. If you
// uncomment joinserver a sample I made will
// be played upon connection to a server. You will
// probably get bored with this quickly so replace
// it with your own
//
// Samples "joinserver.mp3", "startyourvoting.mp3" and
// "endofvote.mp3" were made by me (Mani) using FruityLoops
// and a nice VST plugin synth. The rest are from the
// core HL2 server installation.
//


"joinserver" admin_plugin/actions/joinserver.mp3
"votestart" admin_plugin/actions/startyourvoting.mp3
"voteend" admin_plugin/actions/endofvote.mp3
"roundstart" admin_plugin/actions/roundstart.mp3
"roundend" admin_plugin/actions/roundend.mp3
"restrictedweapon" admin_plugin/actions/restrictedweapon.wav

the mp3 file i wanna put on the server is called... keeping.mp3
i tryed admin_plugin/actions/keeping.mp3

and the file i put in
C:\srcds\cstrike\sound\admin_plugin\actions\

but the console said

Failed to load sound "admin_plugin\actions\keeping.mp3", file probably missing from disk/repository

So please help thx