I have installed the Virtual Box, and I would like to make a Debian virtual machine but I can't do this because my Virtual Box don't allowe me to choose Debian x64. My computer and the .iso file are x64 too, that's why I don't understand why I can't choose it. Somebody can tell me how can I slove this problem?bit

I have installed the Virtual Box, and I would like to make a Debian virtual machine but I can't do this because my Virtual Box don't allow me to choose Debian x64. My computer and the .iso file are x64 too, that's why I don't understand why I can't choose it. How can I solve this problem?