Encoder Output Problems

[Mike]

I have a Grayhill 63R128 encoder, an Atmel STK500 development board and a LeCroy 9354M oscilloscope. I have it hooked up like so:

Encoder Positive In -> 5vdc pin of Atmel Development Board
Encoder Ground -> Ground pin of dev. board
Probe 1 -> Encoder Output A
Probe 2 -> Encoder Output B
Probe 1 Gnd -> Board ground
Probe 2 Gnd -> Board ground

However, it's not returning a square wave back. Here's the o-scope screen dump http://img.photobucket.com/albums/v7...screendump.jpg

Thanks,
Mike