Unrecognised argument "BOOT_IMAGE=windowsOS/wimboot"

[Ritzo]

I try to install windows with wimboot via ipxe and a tftp menu.

I got the following messages incl. error
Loading windowsOS/wimboot ... ready.
wimboot v2.5.2 -- Windows Imaging Format bootloader -- http://ipxe.org/wimboot

Command line: "url=http://<webserver>/tftpboot/windowsOS/boot-ipxe BOOT_IMAGE=windowsOS/wimboot "
Unrecongnised argument "BOOT_IMAGE=windowsOS/wimboot"
Press a key to reboot

tftp-menu
label ctidevw10001
menu label 2016 ipxe wimboot2.5
kernel windowsOS/wimboot
append url=http://<webserver>/tftpboot/windowsOS/boot.ipxe

label ctidevw10011
menu label 2016 ipxe wimboot2.5 linux
LINUX windowsOS/wimboot
append url=http://<webserver>/tftpboot/windowsOS/boot.ipxe

label ctidevw10001
menu label 2016 ipxe wimboot2.5 http
kernel http://<webserver>:/tftpboot/windowsOS/wimboot
append url=http://ctsprdsup001.core.weblocal/tftpboot/windowsOS/boot.ipxe

I did some grep in the windowsOS and wimboot folder and in the txt.cfg-File with the tftp-bootmenu and search for "BOOT_IMAGE"-parameter and I can't find this parameter.

I search and tried serveral advices from other website without success.

Question:
- How do I have to define the tftp-menu, to get wimboot working?
- Where does this Parameter "BOOT_IMAGE" come from.

OS
- Ubuntu xenial with tftpd-hpa, dhcp, ..

Other Linux-systems I can install with the tftp successfully.

Thanks for your advice in advance
Ritzo