I solved the problem. By mistake i deleted default.ipxe file’s last line’s “##params”
I added “##params” and now it is working.
Thanks anyway.
#!ipxe
cpuid --ext 29 && set arch x86_64 || set arch i386
params
param mac0 ${net0/mac}
param arch ${arch}
isset ${net1/mac} && param mac1 ${net1/mac} || goto bootme
isset ${net2/mac} && param mac2 ${net2/mac} || goto bootme
:bootme
chain http://#.#.#.#/fog/service/ipxe/boot.php##params