boot using your example

[NiKiZe]

If you follow the Url in the error message and check them of one by one, you will probably find that your Features line does not contain bzImage support

the iPXE in virtualbox is a limited version (mainly due to virtualbox still imposing a 64K limit on the ROM)
What you need to do is to detect your limited iPXE, load a full iPXE and than have your script run from there.

for an example how to do this via dhcp, with ISC dhcpd, see https://gist.github.com/robinsmidsrod/4008017
If you just want to do this manually then:
after dhcp
run chain http://boot.ipxe.org/ipxe.pxe
then press ctrl-b again and retype dhcp and the rest of your commands just like you did.