Hello Daren,
again a look at the log reveals the problem
On Thu, Jul 02, 2015 at 04:58:14PM +0800, Daren Sin wrote:
spawn qemu-system-x86_64 -no-kvm -cpu core2duo -m 256 -serial mon:stdio > -cdrom var/run/demo.iso couldn't execute "qemu-system-x86_64": no such file or directory
The run tool tries to execute Qemu to run the demo scenario, but the qemu-system-x86_64 binary is missing. On Ubuntu, installing the "qemu-system" package will help, but depending on your Linux distro the package name may differ.
Regards