Windows Live Mail – Birthdays not importing on Backup

Hi:  Here is a problem I see with Windows Live Mail backup of contacts - I worked hard to fill in all the fields that are important to me on my contacts.  One is there birthday - so - after I got my contacts all perfect - I backed them up using the .csv options and selected all the fields available.  Then, I went to another PC and did a import and guess what - NO BIRTHDAYS!  That sucks - even trying import from Google Contacts didn't work - If you have a field in your contacts that has data in it - you should be able to export it and save it or what is the point of having the field there.   This needs to be FIXED