Gift in will cannot do what testator states in will

IN NEED OF ASSISTANCE: I am dealing with the following matter

A testate devised that a property is to be rented and the rent used to maintain minor children, however, the property was unfinished and could not be rented at all. the testator did not leave the absolute interest in the property to anyone in the body of the will. There is a residuary clause.

looking for an authority dealing with a gift left for a particular purpose but cannot perform the purpose and what happens to it.

my position is that the gifts falls to the residue as i was not specifically left to any one and it could not be rent. Other parties are contending that the children would be entitled to a portion of the value of the house equivalent to the rent they would have gotten if the house could have been rented.

Sorry, I started to respond and just realised this was posted 4 years ago!