issue in workflow default approval by primary owner manager

1. Once that workflow is enabled, go to a group in AD and open its Properties.
2. You will see a 'Membership Approval' tab. Place a checkmark in the top box for "Approval by the primary owner".
3. Go to the 'Managed By' tab and specify an owner of the group in the top field next to 'Name'.
4. Have someone try and add a member to this group and it should prompt them to enter a reason for the change.
5. Once the request has been submitted, the owner of the group can log on to the Admin or SelfService web interface and select the Approval link.
6. The group membership request can be seen here and Approved or Rejected.
7. If the request is Approved, go back to the group in AD and see that the member has been added to the group.

in steps 4 ,where user can try its only through web interface .

Adding the user to a group that requires approval can be performed in any interface: MMC or web.