Looking for some help with a security predicate problem. 

Need EA Dashboard to dynamically expose data to various regional managers on an Invoice and Invoice Line Item object (Master Detail)

Using 'OwnerId' == "$User.Id" on the Invoice header object works properly.  Regional Mgrs see only their data.

But can't get security at the Invoice Line item level to work properly.

Added custom formula field on Line Item object that points to the parent Invoice OwnerId (OwnerIdLI__c).

Can't get this security predicate to work  -- 'OwnerIfLI__c' == "$User.Id"   Results in "Can't find an data"

Thanks for any help!