Pitch counter - not allowed

[peter_s_n]

I cannot find anywhere in the LL rulebook where a first base coach is denied use of a pitch counter.
I'm curious..was the kid counting total pitches (pitcher limit?) or was he keeping track of balls and strikes for his manager?
The only reason I could think that the counter was to be removed from the game is if the kid's ball/strike count differed with that of the PU, or if the kids (possibly incorrect) pitch count was used to challenge the PU.