trouble adding hard disk

[fbsd at microhost.su]

Hello everybody!
I have a trouble to add 500G new disk. 
uname: FreeBSD 7.2-RELEASE #0
harddisk connected via SATA controller
======
atapci0: <VIA 6421 SATA150 controller> port
0xb000-0xb00f,0xb400-0xb40f,0xb800-0xb80f,0xbc00-0xbc0f,0xc000-0xc01f,0xc400-0xc4ff
irq 18 at device 0.0 on pci1
======

dmesg | grep ad
=====
ad0: 76319MB <WDC WD800BB-00JHC0 05.01C05> at ata0-master UDMA100
ad4: 476940MB <Seagate ST3500630AS 3.AAK> at ata2-master SATA150
=====

I use sysinstall to setup slice using fdisk and bsdlabel to create
partition.
When I choose to write changes in bsdlabel i got error mounting: no such
file or directory.
before use sysinstall i create directory.
mkdir /newdisk

after sysinstall i got:
=======
ls | grep ad4
ad4
ad4s1 
=======
But when i doing "newfs -O2 /dev/ad4s1"
i got an error: 
=====
skipped.
976633600
internal error: can't find block in cyl 0
=====
What i'm doing wrong?
Tnanks for all answers :)
Sorry about my english :)