mobile

I tried the one click root script I found on this site and it will not root my device I have tried for close to an hour with no success
every time I run the script I get this error
Starting adb server...
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
Waiting for device...
Device detected!
Pushing files...
4170 KB/s (1048328 bytes in 0.245s)
9 KB/s (9226 bytes in 1.000s)
4836 KB/s (4017098 bytes in 0.811s)
Rebooting...
Looking for LG serial port...
ERROR: The system was unable to find the specified registry key or value.

I have tried different usb cables and different usb ports to no avail.
my phone is running lollipop 5.0.1 the model is an s990
Does anyone know of a solution?