I am using Acrobat X Pro. I scanned a document, put a Digital Signature on it I just created, and then put it into a zipped file using WinZip. I emailed the document to the receipient an one to myself just to see the Digital Signature that was just created in Acrobat X Pro. When I open the email and read the document using AcrobatX Pro and click on the Digital Signature it tells me that the siganature is valid. But, when I open it on a different computer using PDF Software from another company, Nuance, It tells mt that the Digital Signature is invalid or corrupt. I went back to the PC that created it, checked it agailn and it said it was valid. What happened? Why does it show that it is not valid in other programs? Can this be soved?