HL2 - EP2 Rain Soundscape

In my map is heavy rain and thunder. I can’t find a rain soundscape. I don’t wanna use an ambient_generic, the only one there should be is “ep2_outland.rain_loop1”
But it isn’t there for me. Anyone help? D:

when i set it up to play the sound i get can’t find wave file , , do you get that error ??