I would point you towards a few issues with your tests. Some have previously been identified / hinted at already.
Jet/ACE SQL allows both the appropriate SQL format quotes (') as well as the double-quotes ("). Mixing them, as you have, is probably also perfectly acceptable - even if it does look confused.
Acceptable values for the
Interval parameter are listed in the article Cactus linked you to. Neither of "dd" nor "second" is in that list.
Some versions of SQL (T-SQL being an example) don't allow for date literal values and require a properly formatted date string (In such cases they require proper SQL quotes (') as delimiters). Access supports the same DateTime literals in SQL as it does in VBA. These require DateTime (Hash or Octothorp #) indicators and do not require string quotes, of any variety, around them. For more on what is acceptable for DateTimes see
Literal DateTimes and Their Delimiters (#). You'll see there that your date formatting is otherwise optimal. Probably the best of the available standard SQL formats for them. Certainly the one with the least possibility of ambiguity.
I think, between us, we've explained every problem illustrated in your SQL code. I would just add, before I stop, my congratulations for formatting your question such that all the relevant information was available to us at the start.