How Item Approval Privilege is Validated at Role Level
Make sure any role that you add as an approver, or a parent role, has the Approve Item Change Order privilege assigned.
When a role is assigned in the approvers panel of a change order (or change request), and the change is submitted for approval, the application checks whether the Approve Item Change Order privilege (EGO_APPROVE_ITEM_CHANGE_ORDER_PRIV) is assigned to the role (directly or through role inheritance). If it isn't, an error is shown.