I have made it work.
No matter if COM number is 2, 6 or 8.
The main thingi s that COM number must be the same in FES and Laptop.
And one more thing...
My paltop has 3 USB ports.
After making COM numbers, I swapped the cable to other USB port and it worked.
Some times, COM number is busy because it is used by another hardware/software.
You must try swapping to other USB port.