In glancing quickly at your parameters I would say its becuase your pass depth is equal to the depth of your model. As such the first pass it is trying to make is at 0.1875 deep and that is already at the base of your model so there is nothing to rough (as the alowance 0.04" means the deepest it will allow a pass with your current settings is 0.1475")
You will need to specify a pass depth of less than 0.1475 to get any kind of cut (I think?) Not knowing the specifics of what you are cutting it sounds like the model is quite shallow for the size of the part and either only needs a cursory roughing pass or none at all. It may even be better to cut it deeper for more detail (this depends on exactly what you are cutting through). If you want more suggestions send a screen shot of what you are doing and I am sure others will chime in.