Funny Parse Error on Insert

I am getting a parse error on insert and I cant tell why. Anyone better at
SQL what to lend me a hand?

I'm just doing a simple 'INSERT INTO table (x,y) SELECT ...'

Here's my statement and the error.

fdb=> INSERT INTO mfps_action_codes_394 (code,description) SELECT
'$','Dun Notice Printed' WHERE NOT EXISTS (SELECT 1 FROM
mfps_action_codes_394 WERE code = '$');
ERROR: parser: parse error at or near "code"

Note if I remove the WHERE clause from the SELECT it works...

fdb=> INSERT INTO mfps_action_codes_394 (code,description) SELECT '$','Dun
Notice Printed';
INSERT 9751582 1

Why would this happen?