multi-word expression full-text searching

Hello all:

I'm testing all full-text searching possibilities of PostgreSQL and...

Is it possible to search for a multi-word expression?

I can search one or more words:

SELECT id FROM document WHERE to_tsvector('english',text) @@
to_tsquery('english','despite');

SELECT id FROM document WHERE to_tsvector('english',text) @@
to_tsquery('english','despite & subject');

But it seems not be possible to do a query like:

SELECT id FROM document WHERE to_tsvector('english',text) @@
to_tsquery('english','despite this');

to search the documents in which occur the expression "despite this".
This last query gives the following error:

ERROR:  syntax error in tsquery: "despite this"

Is it really impossible to searh a multi-word expression?

Thanks in advance,

  Mario Barcala