rcolman It would not see the serialo port as per error message.
If you have a Mac, connect the iOptron's serial port to the Mac. Then, go to the Apple menu (top left corner of menu bar) and select "About this Mac."
In the small About window, select System Report... .
In the System Report window, select "USB" under the Hardware category. That brings up the USB Device Tree.
Look for the iOptron, and click on the device. And in the bottom right half of the window, you should see the details. Check the Vendor ID (i.e., the USB VID).
Does it show Prolific instead of FTDI (Future Technology Devices International)? The ASIAIR has problems with the Prolific driver, and this might be another of their bugs. You could also try a USB 3 port on ASIAIR, or go through a USB Hub.
If it says FTDI, then the problem is something else.
If the iOptron does not appear in the USB Device Tree (you can refresh the information by typing Command-R), the ASIAIR will also not see the iOptron, and the problem is likely the iOptron port or the USB cable.
Chen