Campagnolo Chorus rear mech setup

Have you got all of the spacers in the right place? Campagnolo cassettes tend to have different spacings as you move up the block. Also sometimes the cable isnt as tight as you think, the shifter starts slipping that first gear as you try to locate the cable. I tend to back off the adjuster screws, set the barrel adjuster somewhere central ie start again. You can try and trick the mech ie push it in a bit as you tighten down the cable, then slack it back off with the adjuster to sit on the 1st sprocket. Sometimes they just never seem to set up right in which case id rather do an extra little half shift to move up the block than have it refuse to go back down again so i set the bias that way.