Cisco CallManager Account for Yealink phone

[74HC244]

Good day to all. Now I'm busy with registry Yealink phones on Cisco Callmanager. The main problem is creating account for Yealink phone (any model) on Cisco Callmanager. If I create an account with username that consists from letters (for example VolodinVN) and input this account in configuration of Yealink phone - there's Not Registered state. But if I create an account that consists from digits (for example 9632) - it successfully registrates and works. I've tried to update soft on phones (I have VP530 and T46), but the problem still exists. What can it be?
Here's the account on CallManager:
   
As you can see - registration saccessfull
   
Here's another account
   
And smthn whong