Applescript for unread mail

Greetings,

A long time ago, I created the following script that I run occasionally, which makes me a cvs file of the sender subject and date of unread messages in a specific mailbox. Been working fine for a couple of years. Of late it is giving me ALL of the messages in the mailbox, rather than just the unread messages. Any idea what might be happening here?

tell application "Mail"

set myAccount to account "Andrew.cmu.edu"

set myMailbox to mailbox "INBOX/@Action/PMW Blog" of myAccount

set myCount to count of messages in myMailbox

set clipboardText to ""

repeat with i from 1 to myCount - 1

set thisMsg to messagei of myMailbox

set f to extract name fromsender of thisMsg

set ff to quoted form of f

set d to date sent of thisMsg

set d to (month of d as integer) & "/" & day of d & "/" & year of d

set s to subject of thisMsg

set ss to RemoveFromString(s, ",") of me

set s to quoted form of ss

if read status of thisMsg is false then

set clipboardText to clipboardText & ff & ", " & s & ", " & d & return

end if

end repeat

do shell script "echo " & clipboardText & " >> ~/Desktop/headers.csv"

do shell script "open ~/Desktop/headers.csv"

--delay 10

--do shell script "rm ~/Desktop/headers.csv"

end tell

--return clipboardText

on RemoveFromString(theText, CharOrString)

local ASTID, theText, CharOrString, lst

set ASTID to AppleScript'stext item delimiters

try

--considering case

if theText does not contain CharOrString then ¬

return theText

set AppleScript'stext item delimiters to CharOrString

set lst to theText'stext items

--end considering

set AppleScript'stext item delimiters to ASTID

return lst as text

on error eMsgnumbereNum

set AppleScript'stext item delimiters to ASTID

error "Can't RemoveFromString: " & eMsgnumbereNum

end try

end RemoveFromString