安装NFS服务的问题,续,大侠救我!!!

安装NFS服务的问题!
装好了还出现这个问题,我在目标板上设NFS起动,路径为/arca/nfsroot
NFS服务设共享文件夹 属性:读写,主机名用PC的IP192.168.0.18,把远程用户当根用户
目标板启动内核后,初始话的时候出现这样的错误:
Looking up port of RPC 100003/2 on 192.168.0.18
Looking up port of RPC 100005/1 on 192.168.0.18
Root-NFS:Server returned error -13 while mounting /arca/nfsroot
VFS: Unable to mount root fs via NFS .trying floppy.
VFS: Cannot open root device \"nfs\" or 02:00
please append a correct \"root=\" boot option
Kernel panic: VFS:Unable to mount root fs on 02:00

大虾们指点,谢谢!