98SE says invalive Drive after creating primary DOS Partitio

[Windows98SE]

Hi!
I have an non bootable WIndows98SE Installation to install on Virtual Box in DVD and I bootet up with another Win98 CD. I have created an primary DOS partition with fdisk. When I show up the Infos I see it's there named C:. But when I try to format it, it says "invalid drive". And when I start setup it says "can't create temporary folder".

What could be the Problem?

Christoph

[vbox4me2]

Did you use the correct format commands? isn't the VDI made too large for format to handle? You could attach this VDI to another existing VM and format it fat32 from there.