SQL JOIN Problem

[eluser]Unknown[/eluser]
Hi all, i encounter this error

A Database Error Occurred

Error Number: 1052

Column 'id' in where clause is ambiguous

Please help

Code:

$this->db->select('a.id AS id, a.name AS name,
                            a.content AS content, a.pic AS pic,
                            a.click AS click, a.rate AS rate,
                            a.ratenum AS ratenum, a.review AS review,
                            a.year AS year, a.director AS director,
                            a.actor AS actor, a.status AS status, a.recommend AS recommend');
        $this->db->select(b.id AS categoryid, b.name AS category);
        $this->db->select(c.id AS areaid, c.name AS area);
        $this->db->select(d.id AS langid, d.name AS lang);
        $this->db->from(DB_ITEM.'AS a');
        $this->db->join(DB_CATEGORY.'AS b', 'a.category = b.id');
        $this->db->join(DB_AREA.'AS c', 'a.area = c.id');
        $this->db->join(DB_LANG.'AS d', 'a.lang = d.id');
        $this->db->where('a.id', $id);

[eluser]pistolPete[/eluser]
Did you check the generated query?

Code:

$this->db->last_query();