active directory user change password

Question

when i am try to change password to an active directory user using the following code i am getting the the exception
 

//string OldPassword, string NewPassword)
 
try
{
entry.Invoke("ChangePassword", object[] password);
entry.CommitChanges();
}
 

Configuration information could not be read from the domain controller, either because the machine is unavailable, or access has been denied