NHRP Hub incomplete entries

I am having problem at NHRP incomplete entries at hub router:

HUB
ver ios 12.4.20T
!
interface Tunnel0
 ip address 192.168.1.1 255.255.255.0
 no ip redirects
 ip nhrp authentication cisco
 ip nhrp map multicast dynamic
 ip nhrp network-id 1
 ip nhrp holdtime 600
 tunnel source 172.31.1.2
 tunnel mode gre multipoint
 tunnel key 1
end
!
Spoke 1
ver ios 12.4.20T
!
interface Tunnel0
 ip address 192.168.1.2 255.255.255.0
 no ip redirects
 ip nhrp authentication cisco
 ip nhrp map 192.168.1.1 172.31.1.2
 ip nhrp map multicast 172.31.1.2
 ip nhrp network-id 1
 ip nhrp holdtime 600
 ip nhrp nhs 192.168.1.1
 tunnel source 172.31.2.2
 tunnel mode gre multipoint

Spoke 2
ver 12.4(7)
!
interface Tunnel0
 ip address 192.168.1.3 255.255.255.0
 no ip redirects
 ip nhrp authentication cisco
 ip nhrp map 192.168.1.1 172.31.1.2
 ip nhrp map multicast 172.31.1.2
 ip nhrp network-id 1
 ip nhrp holdtime 600
 ip nhrp nhs 192.168.1.1
 tunnel source 172.31.3.2
 tunnel mode gre multipoint
 tunnel key 1

All physical ips are reachable ..

Hub
HQ-Router#sh ip nhrp
192.168.1.1/32
   Tunnel0 created 00:00:21, expire 00:02:43
   Type: incomplete, Flags: negative
   Cache hits: 2
192.168.1.2/32
   Tunnel0 created 00:00:19, expire 00:02:45
   Type: incomplete, Flags: negative
   Cache hits: 5
Spokes
B2-Router#sh ip nhrp
192.168.1.1/32 via 192.168.1.1
   Tunnel0 created 01:22:18, never expire
   Type: static, Flags: used
   NBMA address: 172.31.1.2

Any idea what I am doing wrong here.

-- 
Best Regards,
Mohammed Shoeb Ahmed
Sr. Consultant,
CCIE 18379
Blogs and organic groups at http://www.ccie.net