Custom Soundscript not working

I trying to add a soundscript for my map but they aren't working.
I'm getting this error: CSoundEmitterSystemBase::GetParametersForSound: No such sound mvm_tunnels.base_siren

This is the sound i'm trying to use. The soundscript file is saved in the maps folder with this name: <map name>_level_sounds.txt

Code:

"mvm_tunnels.base_siren"
{
    "channel"        "CHAN_AUTO"
    "volume"        "VOL_NORM"
    "pitch"            "PITCH_NORM"
    "soundlevel"    "SNDLVL_130dB"
    "wave"            "mvm_tunnels/base_alarm1.wav"
}