Someone already deleted their account. How come i can't use their username? I really want the username. T_T

I was about to sign up as a new member on twitter, however, the username i pursue is already taken. Therefore i try to visit the page. There, i see an account with only 5 followers. I began to question,"is this account inactive or is it abandoned by the owner." I found a name in the account and try to search for the owner in one of social networks, and i found her. I began to send her a message and asked her about how is the account, and she said,"I have never used it anymore. You can have it." and i asked her to delete the account and she did. I said thank you and try to sign up again. However, an oddity came up, the twitter keep saying that the user name is already taken, while the owner already deleted it and sure that she will never use it again. Will twitter process such condition? because i really really want that username. THANK YOU SO MUCH.