Full text t_tsquery is giving error

I am getting the following results:

select * from ts_debug('Rumman (AI)');

alias | description | token | dictionaries | dictionary |
lexemes
-----------+-----------------+--------+--------------------+--------------+----------
asciiword | Word, all ASCII | Rumman | {syn,english_stem} | english_stem |
{rumman}
blank | Space symbols | ( | {} | |
asciiword | Word, all ASCII | AI | {syn,english_stem} | english_stem |
{ai}
blank | Space symbols | ) | {} | |
(4 rows)

But,

select to_tsquery('Rumman (AI)');

ERROR: syntax error in tsquery: "Rumman (AI)"

I don't know why this is happening.
Any idea please.