I am using Zimbra Version 8.0.0_GA_5434.FOSS, I am using External Active Directory Authentication which is working fine, I am trying to use ADpassword zimlet

ADPassword | Zimbra :: Gallery

I have made the setting as per the above link however user's are not able to change the password, it is giving the error Permission denied.

Can anyone give me the proper settings or is there any other alternate in zimbra 8 ZCS.