Phone won't register-need to reset phone SIP Password?

We just moved to a new server (need a quiet machine as we are in a temp office and the machine sits next to my desk) and I got some of the phones online quickly, and some refuse, and one took a little longer.

Basically I just set up the extensions but didn’t reset the Device Options>Secret field and the first few phones were fine (for example, my extension has the long alphanumeric string that was autofilled but I certainly didn’t add anything to the phone side). But I have one phone that I needed to reset that secret to something I could type. And yet another that worked after just resetting the phone (just pulled the plug and swapped ports in the PoE switch). And except for the one phone I had to explicitly reset, I haven’t set the secret field on any of the phones. Seems odd to me, but I’m not sure whether or not that should be a requirement or is there a hole in there.

Anyone have any insight?