I have found that in several of my families. The case could be that the name was spelled wrong by either the census taker or the transcriber. As well as you, I have searched census records page by page because the name may not be spelled correctly in census records and the search system does not find the family. I also have several of my families which I have never found in the 1870 census records in Walker County, Alabama. The census records may not be complete. I have found duplicate records and pages in Township 12 and 15 by looking at them page by page. . . so whether pages were not scanned I do not know but the families can be found in 1850, 1860, 1880 and 1900 but not in the 1870 census record for Walker County, Alabama.