I'm trying to threadmill on our old hardinge vmc600 for the first time and having issues. Fanuc control.

1/2-14 NPT
304ss
1/2 dia threadmill solid carbide 4 flute tapered
I've tried a generated g-code from the guhring website and it gives me a 041 cutter comp alarm
The program is using incremental, drops the threadmill in, turns comp on with a g3 move, then spirals out.
I've never done any threadmilling before but really want to, especially for this tough pipe thread in 304ss.
Can anyone give me some tips. We don't have cad/cam, I write all our programs.
Thanks