Cisco WAN :: 861 SSH / Telnet Privilege Exec Level 15 Enable Not Working?

I have a customer with a 861 ISR.I want to block all the privilege 0 users from access the enable command
 
If i telnet into the device, as a priv=0, enable does not work
If i telnet into the device, as a priv=15, enable does work 
If i telnet into the device, as a priv=0, enable does not work
If i telnet into the device, as a priv=15, enable does not work
  
I have issued the command:privilege exec level 15 enable Should block everyone except 15's from accessing the enable command SSH and TELNET are on the same vty:
 
line con 0
login authentication local_authen
no modem enable
line aux 0
line vty 0 3

[code]....
 
Basically TELNET is following the rules ( priv=0 not allowed to access enable ) but SSH is not following the rules ( both priv=15 and priv=0 cannot access the command ) is there a way from blocking somes users from login in completely?