Bad mask /29 for address

Today I switched from a dynamic IP to a block of 5 static IPs from AT&T.  I went into my config to change the int dialer 1 from dynamic to IP.

conf t
int dialer 1
ip address 99.28.107.224 255.255.255.248

and the router proceeded to tell me:

Bad mask /29 for address 99.28.107.224

Maybe I'm missing something in my config.  AT&T has confirmed both the IP address and the subnet.  Below is my current config.


Using 2333 out of 29688 bytes
!
version 12.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Grasshopper
!
logging queue-limit 100
enable secret 5 xxxxxxxxxxxxxxxxxxxxxxxxxxxx
enable password parisfr
!
username admin privilege 15 secret 5 xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
username iwindon privilege 15 secret 5 xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
memory-size iomem 10
aaa new-model
!
!
aaa session-id common
ip subnet-zero
!
!
ip name-server 68.94.156.1
ip name-server 68.94.157.1
ip dhcp excluded-address 192.168.1.1
ip dhcp excluded-address 192.168.1.254
ip dhcp excluded-address 192.168.1.2
ip dhcp excluded-address 192.168.1.3
ip dhcp excluded-address 192.168.1.4
ip dhcp excluded-address 192.168.1.5
ip dhcp excluded-address 192.168.1.6
ip dhcp excluded-address 192.168.1.7
ip dhcp excluded-address 192.168.1.8
ip dhcp excluded-address 192.168.1.9
!
ip dhcp pool local
   import all
   network 192.168.1.0 255.255.255.0
   default-router 192.168.1.1
!
vpdn enable
!
vpdn-group pppoe
 request-dialin
  protocol pppoe
!
!
!
!
!        
!
!
!
!
!
no voice hpi capture buffer
no voice hpi capture destination
!
!
mta receive maximum-recipients 0
!
!
!
!
interface ATM0/0
 no ip address
 no ip mroute-cache
 no atm ilmi-keepalive
 pvc 0/35
  pppoe-client dial-pool-number 1
 !
 dsl operating-mode auto
!
interface FastEthernet0/0
 ip address 192.168.1.1 255.255.255.0
 ip nat inside
 ip tcp adjust-mss 1452
 no ip mroute-cache
 duplex auto
 speed auto
!
interface Dialer1
 mtu 1492
 ip address negotiated <<-- this is where I'm trying to change from dynamic to static.
 ip nat outside
 encapsulation ppp
 no ip mroute-cache
 dialer pool 1
 ppp pap sent-username attreg@att.net password 0 attreg <<-- temp username and passwords
 ppp ipcp dns request
 ppp ipcp wins request
 ppp ipcp address accept
!
ip nat inside source list 1 interface Dialer1 overload
ip http server
ip http authentication local
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer1
ip route 192.168.1.0 255.255.255.0 FastEthernet0/0
!        
!
!
access-list 1 permit any
access-list 101 permit udp any any eq domain
access-list 101 permit udp any eq domain any
dialer-list 1 protocol ip permit
!
radius-server authorization permit missing Service-Type
call rsvp-sync
!
!
mgcp profile default
!
!
!
dial-peer cor custom
!
!
!
privilege configure level 15 line
!
line con 0
line aux 0
line vty 0 4
 privilege level 15
 password xxxxxxxxxx
!
!
end

Any ideas?

Ivan