[Don Reid]

This sounds strangely like a problem I just had. It turned out that nothing was wrong with the encoder code (of course), just a printf statement.

Note that Get_Right_Encoder_count() returns a long! So you cannot
just put it into a printf with a %d type. If you have 2 %ds, you will
get 1/2 of the long for each one, the upper part is usually 0.

The thing to do is to use %ld to let printf know to expect a long value.