I always get "Communication Failure" error. I have changed USB connection cables between UPS and PC, computers with different versions of Windows (XP, 8.1), Firewall off. But no response, the problem still exists.
You have to change some settings in UPSmart if you keep receiving the Communication Fail error. I've downloaded the PDF guide and it appears that it provides some insight into the different configuration methods regarding connectivity.
I recommend downloading the PDF file from the following link to check the mentioned settings.