RAIDCFG to create RAID-10

I'm trying to use RAIDCFG in a WinPE environment to configure a PowerEdge R710 with a Perc 6/i controller.
The system has 8x 278GB SAS disks.
I successfully created a RAID-1 vdisk consisting of 0:0:1 and 0:1:1 using the following command:
raidcfg -ctrl -ac=cvd -c=0 -ad=0:0:1,0:1:1 -r=1

Now I want to create a RAID-10 vdisk using either 4 or 6 of the remaining unused disks but when I try this:
raidcfg -ctrl -ac=cvd -c=0 -ad=0:2:1,0:3:1,0:4:1,0:5:1 -r=10
it says "Unable to determin optimum size for Virtual disk..."

If I try specifying the size (-sz=557) it tells me that it requires the entire disk space and the -sz parameter is not needed.

I have verified that all the disks are the same and all have 100% avail space (as shown when i run: raidcfg adisk -c=0).
I cannot get a RAID-10 vdisk created no matter what I do.

Can someone help???

Thanks.