(1) Are you ready? (2) Are you included? (3) Are you acceptable? (4) How is your timing?
(4) How is your timing?

Are You in the Right Place at the Right Time?

Even if you have a high promotability, a stagnant company doesn't produce many openings, and is reluctant to incur the expense of creating them. (The option is to become an advocate for change and thus be considered a possible solution.)

Bosses can pull you along in your advancement, or sit there as giant roadblocks. (Although, if you are sufficiently valuable, a company will create an opening for you.)

An organization doesn't want to create a "hole" in the organization chart. Not only should your promotion be logical, but so should the one that will fill the "hole" left by your promotion.