length and alphanumeric formula (quick formula question)

Thanks ragulduy, great idea!

I used your formula, I moved columns A/B to Q/R
=AND(LEN(Q2)<=16,ISNUMBER(SUM(IF(FIND(MID(Q2,ROW(Q$2:Q$401),1),"0123456789abcdefghijklmnopqrstuvwxyz",1),1,0))),LEN(R2)<=16,ISNUMBER(SUM(IF(FIND(MID(R2,ROW(R$2:R$401),1),"0123456789abcdefghijklmnopqrstuvwxyz",1),1,0))))

it's working for some of the fields and for some it's not.

E.g.
(it's picking false for the following even though it should say True)

PASUPINVHPCM08



What am I doing wrong?