prophet 5 desktop knobs take lots of turning before doing anything ?

So I already own a pro 5 keyboard and thought I would add a desktop to my set up but the desktop seems so odd and finicky put to my keyboard pro 5, the knobs need turning back and forth multiple times before they do anything making them basically useless , any ideas what this is about ?
I have also been getting voice 5 sounding weird put to the other voices , never had this problem on my keyboard version.

Regarding your first issue, perhaps that's a matter of adjusting Pot mode...?

Globals - Bottom Row
1. Pot Mode: REL, Pas, Jup (Relative, Passthru, Jump)—There are three pot
(potentiometer) modes to determine how the synth reacts when the programmable parameters are edited. (Master volume is not programmable, so these
modes don’t apply.)
In Relative mode, changes are relative to the stored setting. In Relative mode, the
full value range is not available until either the minimum or maximum value and
the respective lower or upper limit of the pot’s travel is reached. For example,
the resonance parameter has an internal value range of 0 to 127. Let’s
say the physical position of the resonance pot is the equivalent to an
internal value of 100. If you switch to a program that has a stored Resonance value of 63 and turn the pot all the way up, it will only go to 90.
To get to the maximum value of 127, you first have to turn down until the
value is at the other extreme and the pot is at the limit of its travel (in this
case, 0 and fully counter-clockwise, respectively).
Prophet-5 User’s Guide Global Settings 15
In Passthru mode, turning the pot has no effect until after the edited
value equals the preset value (that is, until the edited value “passes
through” the stored value).
Jump mode uses an absolute value based upon the position of the pot
when edited: turn a pot and the value jumps immediately from the stored
value to the edited value.

Thanks for that :)
it worked !