128 vs 256 encoders

We are trying to use the Greyhill 63R encoders. We have some 256 pulses, and some with 128 pulses.
The 256 once work fine, but the 128 once just don’t communicate at all. We are usind the Java libraries.
Any help?
We checked the 128 encoders with an osciloscope and they are fine. So are our cables. (i.e, same cables plugged into the 256 encoders works, but with the 128 on it doesn’t).

Please explain in a little more detail what you mean by “don’t communicate”.

What observations are you making that don’t agree with what you expected to see?

We are using the get() function, and it returns a value of 0.
When used with the 256 encoders, we recieve values.