No one should expect good results mixing Campy and Shimano cassettes and drivetrains. Campy's spacing has always been wider 4.55mm for 9 speed and 4.12mm for 10 speed. Shimano is 4.32 and 3.95mm. The small difference accumulates to a larger amount after every shift.
The cable pulls and RD actuation ratios are also entirely different. That's where a shiftmate comes into play - to change the cable pull so the RD produces the correct movement.