Cannot create BFS partition on GPT drive

I made some room on a Hackintosh drive (GPT drive) for 2 FAT32 partitions (as placeholders). I booted up the latest Haiku Nightly off of a USB pen drive. I went to the GPT drive (with DriveSetup) and can see the 2 FAT partitions. I tried selecting either one and could not reformat either one with a BFS file system. DriveSetup said both were read-only.

Is it not possible to make them writable so they can be reformatted? I tried to bring up GPARTED off of a CD but could not find any way to mark them as writable. In Windows 7, same thing.

Anyone run into this problem before?