This error occurs when using the backplane driver for the MVI56-ADM, and MVI56-ADMNET, and you have not executed (installed) the actual backplane device driver. The device driver is activated by calling the program mvi56bp.exe, and mvi56dd.exe in your config.sys system file. Note that this driver must be running before you attempt to launch your program, or call any of the backplane API calls. This driver is required to allow your application to communicate on the backplane.
A Sample config.sys file looks something like the example below:
IRQPRIORITY=1 SYSTEMPOOL=60000 STACKS=10 SHELL=A:\TINYCMD.COM /s /p INSTALL=A:\MVI56bp.exe INSTALL=A:\MVI56dd.exe
The disk.ima attached to this article is an example ADM/ADMNET boot floppy that can be used for reference.