Infrastructure Software

OK,I follow the official documents step by step,I installed the vdi 3.4 in Oracle Linux 5.7(oraclevdi.jiayutester.com),then installed a window server 2008 r2 64bit(jiayudc.jiayutester.com) that made it to be the Domain Controller(jiayutester.com) and DNS,at the end,I edit the /etc/krb5.conf.I execute the following commands:
1.getent hosts jiayudc.jiayutester.com
*****
*****
--------------------My Note:Normal-----------
2.kinit -V administrator@jiayutester.com
Authenticated to Kerberos v5

This is my krb5.conf------------------------------------
[logging]
default = FILE:/var/log/krb5libs.log
kdc = FILE:/var/log/krb5kdc.log
admin_server = FILE:/var/log/kadmind.log

[libdefaults]
default_realm = JIAYUTESTER.COM
default_checksum = rsa-md5
dns_lookup_realm = true
dns_lookup_kdc = true
ticket_lifetime = 24h
forwardable = yes

[realms]
JIAYUTESTER.COM = {
kdc = space-21pel8ghu.jiayutester.com
admin_server = space-21pel8ghu.jiayu.com:749
default_domain = jiayutester.com
}

[domain_realm]
.jiayutester.com = JIAYUTESTER.COM
jiayutester.com = JIAYUTESTER.COM

[appdefaults]
pam = {
debug = false
ticket_lifetime = 36000
renew_lifetime = 36000
forwardable = true
krb4_convert = false
}


Then,I login to the web console to set company, I select Active Directory to use as User Directory,then I fill up all the needed information(I am sure that all the information I fill in the form is correct),when I click the next,error occured....it's the context:

Unable to Connect to User Directory
Failed to connect, no servers available

Now,I searched everywhere for information,but I can't resolve the problem...Please help me,smart guys