That tells us the G-Code file itself is fine. If you were to open the G Viewer, you should see the simulated motion.
If you open KMotion (not KMotionCNC), there is an option to display the Console-
Attachment 455340
This will often show more information about why GCode has been aborted, for example if an axis disables for some reason, the KFlop will output a message to the console saying what axis disabled, whereas KMotionCNC will simply tell you GCode has been aborted.
However buffer errors are not something I know anything about, so I'll let Tom suggest why you're receiving them.