Cannot close a secondary page launch from level 1 grid in the Payment Request lines page

Hi, I am hoping someone can provide me with help on this. Our business users wanted me do a customization to the fluid payment request component to add attachments at the PR line level, which I thought would be quite easy, however I am now stuck because the page will not close when I click on the Done button, it does close if I click the cancel button.

Basically, I cloned the attachment secondary page at the header level and just called it from a button at the PR LInes grid, calling the DoModalPopup, when clicking the done button executes EndModal(1), reading PeopleBooks, this causes data on the secondary page to be copied by to component buffer and SaveEdit to execute. When clicking Cancel, the code executes EndModal(0), which just closes the secondary page, nothing is copied back.