E Drive, cannot select the drive I need

I had set up an e drive on a partition of an external drive, and it worked fine and I could boot from it.
However, I read in the instructions that the File Vault needed to be off when you made the drive. I had it on at the time.

I turned the FIle Vault off, then tried to remove the e drive to create another one, but I couldn't.
I reformatted that partition to get rid of it and tried to re-create the e drive.
The problem is I cannot select the drive now.
How do I fix this?