Hey Amr,
When integrating UC with LDAP, anytime there is a change or addition on the LDAP Authentication page, Cisco IMAP on CUC needs to be restarted.
Please go ahead and restart IMAP Server by going to Serviceability page of UC.
After IMAP is restarted, you can verify by logging to IMAP from command line of workstation
Start -> Run -> cmd
telnet 143
1 login <userid> <password>
Here you replace the IP address and the credentials with AD credentials
As an example if UC is 10.0.0.1 and end user is jdoe and password is cisco123, you can run the following to test IMAP connection:
telnet 10.0.0.1 143
1 login jdoe cisco123
If you get login successful then IMAP is all good now and you can use Cisco Mobile 8.
If IMAP still fails and you are using CUC 8.5 or higher, you may want to check the bottom of this post regarding the OS Secure Status:
https://supportforums.cisco.com/docs/DOC-24554
Let me know how it goes.
Regards,
Jas