dalchina thank you for your help. But it turns out that wasn't the problem.

I managed to get this to work.
First I assigned a letter to a partition"(Disk 0 partition 2)" that was in FAT32...then...

I wanted to activate BitLocker on C: partition....But when I tried, I got this message:
"BitLocker Setup requires the drive file system to be NTFS. Convert the file system and run BitLocker Setup...