iPXE with SCCM Chaining

[bshogeman]

Changing the DHCP scope settings, booting iPXE and loading a script from a HTTP server all are no problem.. But now chaining SCCM..

Script used in php:
<?php
header ( "Content-type: text/plain" );
echo "#!gpxe\n\n";
echo "isset \${ip} || dhcp || echo DHCP failed\n";
echo "prompt --key 0x02 --timeout 2000 Press Ctrl-B for the iPXE command line... && shell ||\n";
echo "imgfree\n";
echo "set next-server 172.20.52.1\n";
echo "echo Asset: \${asset} Serial: \${serial}.\n";
echo "cpuid --ext 29 && set arch x64 || set arch x86\n";
echo "chain boot\\\${arch}\wdsnbp.com\n";
echo "boot\n";
echo "exit\n";
?>

Just as simple as possible for the moment..
Where it failed is the chain loading. It gives a file not found.
When pressing Ctrl-B and give above command's by hand there is no problem. The F12 prompt from SCCM is shown with all other useless info sccm always gives at the prompt. But from the script it is a problem.
Except when you embed it, then it runs fine as well, but then the webserver don't get the request with the additional strings and the whole point of using ipxe is gone.

What can be the problem?
Why load iPXE in between? I use the script url to pass some variables to a inventory database. Yes this isn't shown in above php script yet but let it work first And at the last point if all works fine add a option to boot a simple freedos image for bios maintanance.