Why can't my not fully hatched baby chick peep?!!

[lucyz]

Its head it out of the egg, day 21. Still mostly in, but it can't PEEP! my other one is peeping up a storm but this one isn't, it opens its beak, but nothing comes out. HELP D:

 

[Barrdwing]

Is it trying to peep, or is it breathing with its beak open? How long has it been since pip--does it look like it's stuck to the shell?