KO BE questions

I compared KO's BE with AO11 with ACE side count and ZEN in single deck playing about 500 rounds.

I have observed for KO's RC at 2 and 3 it seems to overestimate
the advantage for betting because corresponding TC's for AO11 and ZEN
are either zero or negative sometimes but at pivot(RC=4) its very accurate.

Which is correct ? ZEN seems to differ a lot compared to AO11.

Thanks,
KOKO