Oh....Thanks malpensa, I am new to DSM. I will try what you said...
My update...
I can install DSM to VM now, during the installation. it asked me to reboot, but after rebooting, I got error 22. I shut down my VM and copied your vhd again and overwrite, then I restarted the VM, but after loading/install something, VM and Synology assistant just shown timeout, looks like Synology assistant can not find or access the VM after rebooting, I also cannot ping the VM.., any idea??