The grantor (seller) on a deed may not be a "person" but rather someone acting in an official legal or capacity. I could not find one ancestor's deed "selling" his farm because it was transferred on a deed executed by the local judge after a court action involving his estate. The judge was the grantor, not the ancestor and not his children. If your ancestor went through a a foreclosure or a sale of property for back taxes, the court or the local sheriff may have been the grantor on the deed transferring property from your relative's ownership.
If you cannot find a deed of sale, look for a court action involving your ancestor or his estate.