ORDER BY clause in SQLite working erratically using fts4

My Full Text Search using sqlite3 with fts4 is working perfectly, but the ordering is behaving erratically. A few items in the middle (and in the end) of the results are misplaced.

I'm using this search query:

SELECT * FROM MyFTSTable WHERE [search term] ORDER BY BookID ASC, Chapter ASC, Paragraph ASC

Being BookID, Chapter and Paragraph of int type.

I created the Virtual Table like so:

CREATE VIRTUAL TABLE MyFTSTable USING fts4(id integer PRIMARY KEY, BookID integer, Chapter integer, Paragraph integer, Text text, order=ASC)

Any ideas why this is happening?