Upload of email from Windows Live Mail fails

I have setup an OUTLOOK.COM email account

I previously used Windows Live Mail installed on my laptop

I started to upload my emails from Windows Live Mail to Outlook.com

Nearly all of my inbox uploaded successfully but none on my SENT emails uploaded and some Inbox emails also failed to upload.

I get the message below.

Every time I "Try Again" I get the same results

I can send and receive emails using the Outlook.com account without problem.

Any ideas?

Joe