creating crop marks for bleeds using print preview

trying to understand the intended purpose of the bleed and crop marks option accessed from the print preview window. i was hoping that with the below illustrated settings, the crop marks would align to the black lines of my below image but as you can see they do not. instead, they are somewhat aligned to the document edge and are not inset the .125" as designated.  i have inserted the black lines .125" from the document edge as an experiment