How was your antenna placement? Was the rx tucked in with a bunch of wires or next to any carbon etc?
I just read an interesting article in RC Soaring digest where they did a number of tests on 2.4 antenna placement issues.
One thing they noted was that having the rx antenna laying up next to another wire - like a servo lead or balance plug lead or any other metal or any carbon fiber etc - would de-tune the antenna and drastically reduce range.
Even a small spacing made a big difference. It pretty much had to be touching to cause problems.
On the other hand, Ive seen many a 2.4 install where the rx was tucked into a nest of wires and there seemed to be no issues at all, but its something to note.