You have searched and searched but you can’t find certain families in all the Census records.
The most likely reason is that the names you are searching for are not the names that were recorded in that Census. There may have been verbal transcription errors. There may have been indexing errors. For details see the post: What were their names?
Here are a few strategies to locate the missing families. Continue reading
This is a special case. You can search for people in the 1905 NY State Census at ancestry.com. Until recently, But, you probably would not find anyone because ancestry had only a few NY State counties available online. During 2014 ancestry updated their 1905 NYS census and now have most of the counties available. Read their db description since they state that the records for some counties were lost.
For the 1905 NYS Census, you can also go to SteveMorse and search by name. It is a different index and search engine that might yield different results.