[GENERAL] tsquery error

The following query give the error:

select
id,title,dtype,source,used_for,ts_headline('english',content,to_tsquery('english','
ma waterflux'),'minWords = 99, maxWords = 999') from info where  clob @@
to_tsquery('english',' ma waterflux') order by title,dtype,source,used_for;
ERROR:  syntax error in tsquery: " ma waterflux"

Remove either the "ma" or the "waterflux" and the query works.

What is causing the error?

(MA Waterflux is a product name.)

Cheers and thanks,
Stephen