China DOS Union

I want to use the vm virtual machine to test a DOS boot USB drive (without PE). The vm can only mount the USB drive as a SCSI device to boot, so there is a lack of drivers under DOS and cannot enter the system. I have extracted vmscsi.sys from the vm installation directory to the root directory of the USB drive, and used device=vmscsi.sys to load it in config.sys, but it still doesn't work. The prompt is: invalid system disk, replace the disk, then press any key.
I downloaded an ASPIDISK.exe and used it in config.sys, still no good.
Is there any friend who knows how to solve it?

The specific experiment done is as follows:
Use USB-ZIP mode to make a PE boot USB drive and a DOS boot USB drive respectively. Let's call the PE one USB drive 1 and the DOS one USB drive 2.
Experiment 1: USB drive 1 starts successfully on vm;
Experiment 2: USB drive 2 fails to start on vm, prompting invalid system;
Experiment 3: USB drive 2 can start successfully on the real computer.
The comparison between Experiment 1 and Experiment 2 shows that vm supports the USB drive to start in USB-ZIP mode. The comparison between Experiment 2 and Experiment 3 shows that the difference between the real computer and the virtual machine vm is that the virtual machine recognizes the USB drive as a SCSI device, and the lack of SCSI drivers under DOS.
Note: The virtual machine is the latest full version of VM7.0
The USB drive is 1G in size, made with usboot1.70 for USB-ZIP boot, and starts successfully on multiple real computers

ASPIDISK.exe is the dosdrvr.exe downloaded in the following post
http://www.cn-dos.net/forum/viewthread.php?tid=37876&fpage=1&highlight=ASPI

Ask, my bootable disk is PE + DOS. After booting, it automatically enters PE. How to enter DOS?！