Sometimes, this is because they do not really have the money, but do not want to disappoint you now. However, waiting until April to break that news tends to be worse than giving it before you finalize your applications.
It also means that you or anyone else cannot answer the question you posed now, since you need more information from them (i.e. how much they are willing to contribute without parent or cosigned loans and without compromising your sibling’s college funding or their retirement) to be able to answer it.
Be prepared to choose a low cost option in case of the likely scenario where they reveal in April that there is no or very little money.