Flexfield Security Rule On Key Account

[jack@oracle]

I have recently defined security rule excluding all the other key accounts to a responsibility to ensure user can access and only one key account ... I am able to populate the entire string as desired.But when I try to checkout the account generator fails...The reason is as I have excluded all the accounts the AP accrual expense account is also excluded ..If I include it works fine...Now I can't restrict the user to 1 account and user can user accrual account also...How can I hide it???