1911 census not very good

[vallee]

I have been trying to find a Ann Elizabeth Wallis born 1856 in Islington
Tried every variation I could think of like including first name starts with A surname starts with W got nothing
Then I remembered she was transcribed as Annie in 1871 so tried just putting Annie in the search and up she came ???
But as it starts with A why didn't it show up sooner ??