Create a new host for bare metal to install ubuntu 12.01, always pending on installation

I installed Foreman 1.7 on CentOS 6.4, then I try to use unattended
installation. In Foreman, I configured TFTP, BMC, DHCP, DNS on this Foreman.
I create a new host for bare metal (Use Cisco UCS Server) to install
ubuntu 12.01, after this host is created, the status is B(pending on
installation).

From proxy log, it just show below info, seems it can recognize this bare
metal server, but no other steps are done.
In bare metal (Use Cisco UCS Server), I just change BIOS boot option as
PXE, and enable IPMI. Is there any other setting I need?
Why Foreman don't start to installation? Any tips? Thanks a lot for help

[root@foreman log]# tail -f /var/log/foreman-proxy/proxy.log
10.74.15.122 - - [18/Dec/2014 20:27:18] "GET /features HTTP/1.1" 200 41
0.0007
10.74.15.122 - - [18/Dec/2014 20:27:21] "GET /serverName HTTP/1.1" 200 29
0.0006
10.74.15.122 - - [18/Dec/2014 20:27:21] "GET /10.74.15.0/70:81:05:ff:32:0c
HTTP/1.1" 200 182 0.0013
10.74.15.122 - - [18/Dec/2014 20:27:21] "GET /10.74.15.0/10.74.15.99
HTTP/1.1" 200 182 0.0020
10.74.15.122 - - [18/Dec/2014 20:27:22] "POST /syslinux/70:81:05:ff:32:0c
HTTP/1.1" 200 - 0.0019
10.74.15.122 - - [18/Dec/2014 20:27:22] "POST /fetch_boot_file HTTP/1.1"
200 - 0.0105
10.74.15.122 - - [18/Dec/2014 20:27:22] "POST /fetch_boot_file HTTP/1.1"
200 - 0.0067
10.74.15.122 - - [18/Dec/2014 20:58:12] "GET /serverName HTTP/1.1" 200 29
0.0030
10.74.15.122 - - [18/Dec/2014 20:58:12] "GET /10.74.15.0/70:81:05:ff:32:0c
HTTP/1.1" 200 182 0.0100
10.74.15.122 - - [18/Dec/2014 20:58:12] "GET /10.74.15.0/10.74.15.99
HTTP/1.1" 200 182 0.0018