Forum:Waters of Life help

In Fallout 3 quest, "Waters of Life"-

Upon meeting Dad and the group from Rivet City outside the Jefferson Memorial, and all the Mutants gone, what is to be done if when Dad asks "is safe in there" and the only provided answer responses are 1. "It's not safe in there yet." or 2. "I'm working on it, okay?"

I cleared out the mutants earlier, and I can't perceive any enemies (perception at 100%) nor can either Dogmeat or Fawkes when they accompany me.

Any suggestions other than trying again from a much earlier save?

Thanks in advance.