It is possible that a relative knew nothing about their grandparents, aunts, uncles, etc. Depending upon how closely they lived to where those relatives lived and how emotionally connected their parent was to their own family, a person may have little knowledge of their relatives.
And no matter how often you ask, it won't change that.
It doesn't mean you don't look for clues, but remember that sometimes people really do know nothing about their mother or father's family. This is particularly true if their mother or father had some reason for not wanting them to know.
There may be little clues--so keep looking.