Technical MOP transform in WoD?

Hello everyone,
I returned after several months of absence , more or less since Molten has given way to Warmane .
I launched my client MOP ( played on Sargeas ) , who worked the last time , and the login screen I am to WoD .
Obviously you are trying to access the e-mail wants , as if he had patched to the official ( but I'm sure you did not do it because the login screen appeared after about 1min , too little to patch ) .
Can anyone help me ? Do you think I have to re-download the entire client or perhaps has broken something ?
P.S. The realmlist is correct and the folder is not in " read-only " ; obviously I launched Wow.exe file .

Thanks for the answers ...