fdisk problem

[Valerio daelli]

Hello everybody
we have a 2235Gb disk which we want to partition.
If we use sysinstall->Configure->Fdisk and try to build a unique slice
we get a message like

'Wrote FDISK partition information out successfully (100%)'

but if we go back to fdisk it shows a freebsd slice of 187Gb
plus an unused slice of 2048Gb.
If we delete it and recreate a new slice, the problem persists.
Is there any tutorial about using fdisk without using sysinstall?
Thanks

Valerio