Reset Password in Active Directory

Hello friends, I am new in LDAP programming and facing a problem related to Reset Password in Active directory from website.
I have to implement a functionality in Share Point enabled ASP.Net website. Using this user can reset their password.
I completed the coding part but getting an exception when running this application at production server.
This application is running for admin account at development server. i.e. only admin (having full access to Active Directory) can reset the their password.
Also this application is giving same error at production server for admin.
exception is "Access is denied."

i am not able to resolve this issue. If you have the answer please respond.

Thanks in advance