VGV7519 over serial TFTP

Hello,

I'm trying to install lede on a vgv7519 but have some trouble. I followed the instructions on openwrt.
Send over serial in uart mode the .asc file
In uboot i did
md.l 0xb0000000 0x1000000
setenv ipaddr 192.168.1.1,
setenv serverip 192.168.1.2
and setenv ethaddr xx:xx:xx:xx:xx:xx
And than tftp 0x80700000 u-boot.bin
But get Unknown command 'tftp' try ' help'
tftp is not regonized as a command...

Any ideas?

Thank
Jeffrey