This email address is already in use with another Apple ID

Hi, I have been having a problem with changing my apple id, as I had two Apple id's and I wanted to use the Email Address which I have for work purpose and official use, the other one which has all my backup and everything in it, was the one I created in my teen, so the Email is very unprofessional, I removed my official Email address from that apple id and when I try to add it to the apple id I currently use it says that 'This Email Address is already in use with another Apple ID" when in fact it is not any more, how do I swtich my official Email Address to my Apple id ? Please help, and Thank you,