Add URL link to documents

[belgiumactuser]

I am trying to find the function to add a link from a url to the documents tab.

Both functions below give the following error: URI formats not supported:

Pdfurl = "http://somewebsite.com/link_to_pdf.pdf"

Dim att = ACTAPP.ActFramework.SupplementalFileManager.CreateShortcutAttachment(Act.Framework.SupplementalFiles.AttachmentMate.History, PdfUrl, "This is the description", False)
Dim at = ACTAPP.ActFramework.SupplementalFileManager.CreateAttachment(Act.Framework.SupplementalFiles.AttachmentMate.History, PdfUrl, "Example", False)

Is it even possible to add a URL link trough SDK?

Thanks.