Did you encounter a situation where digital signing of the document worked correctly but the signature became invalid when you sent the signed document to a recipient? Or when a document sent to you shows that the signature is invalid although the signer says everything seems to be in order?
Antivirus programs attempting to scan the signed file are likely the cause of the problem. When “re-assembling” the file, the antivirus program is unable to put it back the same way and so the message comes up at the destination that the signature is invalid or altered.
What will help to resolve the problem is compressing the file as a zip, rar or other archives.