Bit won’t touch sliding bar

[chkorte]

BIT WON’T TOUCH SLIDING BAR
I have tried several times to cut the attached pattern with no success. I even tried cutting top and back as separate patterns with the same results. Each time the machine measures the length and width just fine, then it asks for the bit, goes to the touch plate then back to front then touches the top of the board but when it goes to measure the board thickness at the sliding bar it doesn’t go down far enough to touch the top of the sliding bar so I get an error telling me to check the sliding bar but the sliding bar is where it should be. I’ve tried formatting the card, re-installing the firmware and re-doing the project but nothing helps. Does anyone have any ideas?