Add custom tool

i have tried to enter a custom tool shape, a 1/8" dia shaft with a 1/16" ball head with 1/2" LOC
so I drew this shape and assigned to the custom tool, it shows in the tool setu the correct looking tool, but when I simulate i get an error
error tool

Hello David,

Use this link to find out how to create custom Mill tools in BobCAD: https://bobcad.com/components/webhelp/BobCADCAMV33/en/Content/Merge/CAM/Tools/Custom_Tools.htm?Highlight=custom%20tool

Thanks!
I see that it is in help, I should have tried first.