Spotify has to be faster with the music. We need the newest music from Spinnin Records. It's pretty annoying that Spotify is so slow and it doesn't have it. I'm dissapointed about this.
As @MattSuda explained, missing or unavailable music is almost always a decision by the artist/label to withhold the content from Spotify. Sometimes it's temporarily unavailable while they sort out legal issues or correct metadata, in which case it'll be back up as soon as they resubmit it to Spotify.
While it might be a good idea to contact the label directly and ask why the music isn't on Spotify, you can also fill out this form to let Spotify staff know of your interest.