Transfer from classic account to BC account ??

Hi,

I used RAF an bought WoW classic. Now i ve some lvl 60 on Classic Accounts and other chars on burning crusade Accounts.
My Question, can i transfer one of my lvl 60 from a classic account ( only some weeks old) to one of my BC Accounts ???
Or mus i upgrade the classic first ??

Thank you !!

You can go from Classic to BC, just not the other way around.