Hi,
In IT0171, while hiring based on your Employee group, the benefit area defaults the values. So, your benefit area would not be eligible for these employees.
Also there is eligibility date in IT0169. Check is it showing any date. Also check the eligibility rules.
Usually it will be done through portal where employee log in to and elects for benefits. It won't be done through back end. However business users can maintain benefits on behalf of employees.
Thanks,
Madhav.