Did you sign up for the Sling TV Cloud DVR beta program and not get an invite? If so, you are not alone.
If you signed up and still want in Sling is set to admit more beta testers soon according to their blog:
“No need to worry. We still have your information logged and appreciate your interest in becoming a beta tester. We will be inviting many more users over the coming weeks, so continue to look out for an email.”