I just re-aimed my dish using the audible beep signal strength meters. Success! Now, even during heavy rain, I get a decent signal. I suffered with horrible reception since the so-called 'professional' installer couldn't do it right.
If you're getting signal readings in the high 80-90s on 101 and 103º satellites, but nothing on 99º, then suggests something is blocking your dish's view of that satellite. Or you have a defective dish LNB or Receiver.
I called direct tv and after they set me up for the locals in my new location for some reason 99 started working without me doing anything else. I move about weekly and never had this problem before, when i get 101 and 103, i always also have 99 without doing anything.