Bootcamp Installation Troubles

i am having great difficulty installing windows through a bootcamp partition.

i have recently installed Macos Mojave on my late 2013 IMAC with a 1TB Fusion drive.

When attempting to install Windows through Bootcamp, I am able to get right up to the point to the Windows setup screen.

I format my Bootcamp partition to prepare the install of windows.

After i do this i receive an error "We couldn't create a new partition or locate an existing one, see the setup log file"

I was able to previously do this successfully on previous Macos but not sure what i am doing wrong now.

Please help

Advice is greatly appreciated.