disc utility and VoiceOver

Hi All, I'm in the process of trying to partition an external hard drive, using Disc Utility. I am "adding a partition" instead of erasing the disc, and creating new partitions from scratch. Having said that, when I "add" a partition, there's a scroll area that comes up. Upon interacting with it, there is the first partition, it's name, and it's size. Then a vertical splitter, and then the second partition, with it's name and size. I cannot edit either the name, or the size of either partition, and from playing with it, the vertical splitter does nothing. Outside of this scroll area, are text fields, reflecting the name and size, etc. but those are dimmed. Any help with this would be greatly appreciated. :) Thanks so much, Rocco