problem with item configuration : Not supported by ZABBIX agent

[brice]

Hi , I have problem configuration , I use zabbix 1.1beta2 but when I use some command , zabbix return Not supported by ZABBIX AGENT

vfs.fs.pfree[/]
net.if.ibytes1[eth0]
system.uptime
tcp_count
vm.memory.free

I'm a new zabbix's user and i have some problem for translation with documentation .

Thanks for the answers .