Proper use of pam_echo

[Big Bacala]

Greetings.  I am trying to understand the subtleties of PAM on a RHEL6 box, and hope I can gain better insight from more experienced list members.  I've been examining the official documentation and been experimenting quite a bit, but to no avail.  Thank you in advance for any insight you may provide...

Starting with a very straightforward PAM password stack:
  password   requisite    pam_cracklib.so minlen=8
  password   sufficient   pam_unix.so sha512 shadow use_authtok


  password   required     pam_deny.so

Simple enough. I believe I understand what happens.  

Now, insert echo's between each line of the above to trace how things work:
  password   optional     pam_echo.so  TEST LINE 1
  password   requisite    pam_cracklib.so minlen=8
  password   optional     pam_echo.so  TEST LINE 2
  password   sufficient   pam_unix.so sha512 shadow use_authtok


  password   optional     pam_echo.so  TEST LINE 3
  password   required     pam_deny.so
and give it a run...
  [username at box}$ passwd
  Changing password for user username
  TEST LINE 1
  TEST LINE 2
  Changing password for username
  (current) UNIX password: <<use incorrect password here to cause failure>>
  TEST LINE 3
  passwd: Authentication token manipulation error
I still believe I understand what's happening. So far, so good.

Now, I use the correct (current) password, but fail to enter an acceptable new password (eg, <8 characters).  TEST LINE 3 does NOT echo to the screen in this case, even though the pam_unix line fails.  I expected it would.  What am I missing?
  [username at box}$ passwd
  Changing password for user username
  TEST LINE 1
  TEST LINE 2
  Changing password for username
  (current) UNIX password: <<enter correct password here>>
  New password: <<enter very short password to make fail>>
  BAD PASSWORD: it is WAY too short
  Password: <<repeat bad password to make it fail>>
  passwd: Authentication token manipulation error

Thank you.
 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/pam-list/attachments/20150324/1e450d20/attachment.htm>