i had an issue with my tuneEcu software not being able to connect it drove me nuts for a while.
i too have the Lonelec cable with their serial to usb adapter.
in the end i uninstalled my usb drivers and the windows version of TuneEcu off my laptop and then re installed drivers and software again.
all is good now no problems at all . but ive noticed that i have to connect all cables to ecu first then switch ignition on, and then start software and lastly then plug the usb into pc.
hope this helps .. the only message i kept on getting was " Could not connect to ecu" or something very similar