AppleScript Mail: Can't make file into type alias

Some advice please. I'm stumped as to why I keep getting "Can't make file into type alias".

I get this both on my latest M1 desktop and older MacBook (El Capitan). Having looked around I believe I have the appropriate script. Thanks in advance.

on run

set PDFpath to (path to desktop as text) & "Bobbycopy.pdf"

tell application "Mail"

set theSubject to "Scores"

set theContent to "something here"

set theAddress to "email address"

set theAttachmentFile to PDFpath

set msg to make new outgoing message with properties {subject:theSubject, content:theContent, visible:true}

tell msg to make new to recipient at end of every to recipient with properties {address:theAddress}

tell msg to make new attachment with properties {file name:theAttachmentFile as alias}

end tell

end run