Signature field disappears

[gaylec54]

When I sent an interactive .pdf form to someone, the two signature fields that were included on the form disappeared when it was e-mailed to them. The regular text fields on the form were unaffected.

The person thought it might be a Mac/PC problem (the form was created on a PC and they have a Mac), but I sent the form to myself at home and opened it on my Mac, and the fields were still there (and functional).

Any ideas as to why the signature fields vanished from their .pdf? Is there some setting on their Mac that needs to be changed to allow them to be displayed?

Thanks!