Codeigniter problem

What is the problem with this codeigniter
I am passing this array

        Array
        (
            [vrnoa] => 6
            [vrdate] => 2013/11/26
            [party_id_co] => Rearmsa asdf
            [remarks] => Remarks go here
            [etype] => navigation
        )

    to the function:

        public function saveStockMain($data)
        {
            $this->db->where('vrnoa',$data['vrnoa']);
            $q = $this->db->get('StockMain');

            if ( $q->num_rows() > 0 ) {
                $this->db->where('vrnoa',$data['vrnoa']);
                $this->db->update('StockMain',$data);
            }
            else {
                $this->db->insert('StockMain',$data);
            }
        }

And it keeps inserting 0 at the party_id_co column in the database, while there isn't 0 in the array that I have passed, there is "Rearmsa asdf".