My remove tool is not removing objects

My remove tool stopped removing objects.  I have tried generative remove and plain remove.  Neither work.  For instance, I am editing a photo of a baseball catcher making a throw.  Off in the distance past the outfield fence is a school bus.  I am trying to remove it, but when the remove tool is used, it does nothing.  It highlights the area and looks like it is doing something, but it makes no changes.  Previously, prior to a couple of days ago, it was working fine.  What happened?