I did a material test in lightburn for leather on my 100W CO2. My setting were Spd 100mm/s min and 200mm/s max - Pwr 11% min and 31% max with 11 x 11 grid. When I ran the test all the boxes engraved at the same depth? When I do a preview and select shade according to power they are all the same color. What am I doing wrong??? Thank in advance!!