How it would not cut? If something does not cut then the machine pushes it down and it will burn through material and break. So obviously its the CAM. Or the bit slips up in the collet. Or you have a backslash of 3mm, but still...

In V carve there is a Start depth and Cut depth. Set this right. Check then the tool itself from the toolpath window as there you can edit passes and so. If all is right there check your Material setup from the tool[ath window, where you set the safe Z and so.

I am looking from Aspire, but in V carve should be the same or similar