Can not add alias

I am having problems adding an alias to my windows live account.  I had two accounts but did not need the newest one as my original is my most used one. I then deleted this new one. The email for the account is something i still use on a regular basis and so i wanted to add that as an alias to my windows live account. However it comes up with an error message that says "This email address is already taken. Please try another." I don't understand this as I have deleted all record for that live account and no longer have any access to it. the only other place i have it listed is a security email. It would really be beneficial for me to have this email as a full alias though. How can i get it on there as it is my email and not taken?