Why is the PDF form not being attached to a Submit form action?

'm having issues with a form with or without digital signatures, this is a description:

Person #1 fills it out (employee request for PTO) and then submits the form to (HR) Person #2

Person #2 (HR) Verifies the request and then submits the form to Person #3 (the boss)

Person #3 Approves with (or without) a digital signature and then Submits the form to HR

My form issues:

When the 1st recipient, (HR) gets the form and tried to open the pdf, they get the following message:

The attached file contains data that was entered into a form. It is not the form itself.

The recipient of this data file should save it locally with a unique name. Adobe Acrobat Professional 7 or later can process this data by importing it back into the blank form or creating a spreadsheet from several data files. See Help in Adobe Acrobat Professional 7 or later for more details.

Why isn't the form being attached?

Thanks for your help.

Debi