Not able to read messages in IMAP account

I need to read messages in a IMAP account configured in Entourage. I
am using following piece of code:

....
...
...
repeat with k in messages of folder InboxFolder of IMAP account
"user6"
set messageName to (subject of k) as string
display dialog messageName
if (messageName = "Meeting") then
return properties of k
exit repeat
end if
end repeat
.....
....
....
..

I get this error:
Can't get every message of folder "INBOX" of IMAP account "user6"

Please show me the way.

Thanks.