VGV7519 over serial TFTP


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,
setenv serverip
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?