Any rig advice? What to improve?

I would need advice as I am not used to this style of fishing. Im loving it so far, but havent cought any carp in a lake full of it (a fisherman close to me caught 21 in a matter of a few hours (!) with pellets. I dont even see any line movement, leaving a little bit of slack line. Planning on buying PVA bags though. Should I add a small split shot? Any other tips? Thanks in advance!