Alphacam Router Z value issue

Greetings everyone,

Im just at work here trying to program a job using Alphacam. Im having a problem with the Z value. Basically, on the Alphacam model the material is set at 12mm(My Z is set to 0 at the bottom of the material). My fixture is 24.2mm. The final thickness of the job is supposed to come out at 11.7mm. When I output the NC code I am only asked for the fixture height & not the material thickness (presumabley because its set on the model), I enter my 24.2 & in the NC code the E3 value comes out at 36.2(Part + Fixture height). All good & well so far. However, when the operator runs the program its coming out exactly 12mm above the 11.7mm that I want. When the operator changes the Z himself on the machine back to 24.2, the job is coming out the way we want it. Any advice on whats going wrong on the programming side would be greatly appreciated.

When you set "Z" levels, are you setting Absolute or Incremental?