USB device not recognized

I am using 20 Venue 8 PRO's in a research project that requires a USB device to be installed.  16 of the tablets have had no issues, but the last four the tablets don't "see" the device when plugged in. I have drivers to install which also work in the other 16, but these four just won't acknowledge that the device is plugged in.  The USB port does work as there is no issue using a thumb drive. 

Any suggestions?