Is the gal you want to impregnate a plantsim? If so, you need to change a setting in Woohooer.

I see you have Traveler installed. Did you previously change any of the "Allowable Travelers" settings?

@icarus: Children who attend the custom military school career attend 7 days a week. Once they age up to teens, it changes to 4 or 5 days though. (Currently playing a family with 1 sim enrolled in that particular "school".)