CaptureMedia won't boot

Hi, just created a capture media (an .iso file) from sccm 2012 r2 following the guide below:

http://technet.microsoft.com/en-us/library/79465d90-4831-4872-96c2-2062d80f5583#BKMK_CreateCaptureMedia

Mounted the iso to the dvd on a VM (VMware) and connected at power-on. In the BIOS dvd is the first boot device.

When the VM boots it did not boot from the capturemedia.iso but straight booted from HDD.

The same winpe boot image is used which works fine in pxe boot.

What I had done wrong?

thanks in advance