problem of partitioning

[Xiong Zhao]

hello,all.after i create a new logical partition using fdisk or cfdisk
and exit with "w",there always comes report saying that re-read table 
failed with error 16:device or resource busy.next time i attempt to mount
the newly created partition it comes error:mount /dev/sdx has wrong major
or minor number.the same thing happens after i reboot the machine.can
anyone give me a hand.

thanks in advance.

james