I split a Pdf in more documents then I add a watermark on every one.
If the file is signed, in the pages where I want to add the watermark the Artifacts property is null and I get the error: Object reference not set to an instance of an object
Obviously, Artifacts is null
But if I do the same operation with a not signed Pdf every thing works fine.
Any suggestion on how to split a signed pdf in more document and add Watermark on every one?