I am making a mistake and can't figure out where it is... here is my function:

=IF(ISBLANK(V6),"",IF((ABS(TODAY()-V6))>=77,IF(ISBLANK(AND(X6,Y6,Z6)),"CHASE","NO"),"NO"))

What I want:
I'd like cell W6 to display the following info:
- if V6 is blank, I want W6 to stay blank as well
- if V6 has a date, I would like W6 to display info "CHASE" if it has been 77+ days since the date in V6 - otherwise, I would like the cell to display info "NO"
- however, and here is the trick, the info "CHASE" should be displaying only if cells X6, Y6 and Z6 (all of them) are blank - once they get populated with dates, I would like the info "CHASE" move back to "NO"

right now, no matter what dates I put in V6 - it never displays "CHASE" - it just gets stuck on "NO"... where am I making a mistake? please help as it's been two days now I have been trying to sort it out and can't find a solution...

thank you,
magda