It is well-known that children don't like to tell about the sexual relations they have with adults. Some results from Sorensen & Snow 1991 illustrate this: 74% unwanted disclosure (i.e. 14% by sexualised behaviour). If the children have told, then in 72% only after denying at first. 22% have later removed their accusations, but 98% of these later told that their previous accusations have been true.
You can imagine how much pressure is there, if a child even after having told tries to deny it again, but mostly without success.