tsearch synonym dictionary problem

I have a tsearch query that does not returns results and I can not see
why. The actual data is:
   7695 s hwy 89
And in my synonym dictionary I have:
   south   s
   highway hwy
So I am expecting to get a row from the query criteria:
   7695 South Highway 89
But I don't. I do get the row with any of the following:
   7695 S Highway 89
   7695 Highway 89


Here's a little more detail. Checking my dictionary:

tc_lands=#  SELECT * FROM ts_debug('english', 'south');
   alias   |   description   | token |        dictionaries        |
dictionary | lexemes
-----------+-----------------+-------+----------------------------+-------------+---------
 asciiword | Word, all ASCII | south | {gis_synonym,english_stem} |
gis_synonym | {s}

tc_lands=#  SELECT * FROM ts_debug('english', 'highway');
   alias   |   description   |  token  |        dictionaries        |
dictionary  | lexemes
-----------+-----------------+---------+----------------------------+-------------+---------
 asciiword | Word, all ASCII | highway | {gis_synonym,english_stem} |
gis_synonym | {hwy}


And the actual query:

SELECT *
FROM parcel_attrib
WHERE txtsrch @@ to_tsquery('7695&south&Highway&89')

Any pointers as to what I am doing wrong would be greatly appreciated.

Regards,
--
Richard Greenwood
richard.greenwood@gmail.com
www.greenwoodmap.com