Can not get laser to cut

i can get the laser to work with laserGRBL but the same project will not cut in lightburn? will trace right and run thru the file and end but it nerver even burns paper let alone wood?

Check a few things
a) did you configure lightburn into mm/min
Edit → settings → mm/min
probably you are in mm/sec

b) Make sure you are using GRBL and not GRBL M3 or LPC

After making sure the units match, then verify that the S Value Max matches the GRBL $30 value: