Hi Chris,

That's because of the reserved tool numbers ShopBot uses. Here's a list:

Head 1 (Z) tools are #1...#19
Head 2 (A) tools are #21...#29 (Only used if you have a 2nd Z)
Drill 1 (Z) tools are #31...#39 (Only used if you have an air drill)
Drill 2 (Z) tools are #41...#49 "
Drill 3 (A) tools are #51...#59 "
Drill 4 (A) tools are #61...#69 "

Hope this helps!