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(dot)greenwood(at)gmail(dot)com
www.greenwoodmap.com