said by Agent 86 :
"Generally, "those high channels" are encrypted, and DTAs aren't allowed to be used for those channels at this time (due to government [over-]regulation)."
The DTAs aren't designed to receive premium channels. They can do "privacy mode" (weak, used for VOD) decryption, but that would only be used for non-premium channels, if it is ever used.
Yup, so in the range the OP mentioned (100-999), probably 100-299, and 500-799 (at least on my system).