what's going wrong

Supplier_model.php

<?php
/**
 * Supplier management library
 * @package Suppliers
 * @author Ryan Marshall <ryan@irealms.co.uk>
 */
class Suppliers_model extends BF_Model {
 
	protected $table          = 'bf_supplier_details';
	protected $key            = 'id';
	protected $alt_table	  = 'bf_supplier_pricing';
	protected $alt_key		  = 'id';
	protected $soft_deletes   = false;
	protected $date_format    = 'int';
	protected $set_created    = false;
	protected $set_modified   = false;  

    public function __construct() {
    }  
	
	/**
	 * Save supplier
	 * @param integer $id Supplier id
	 * @return boolean
	 */
	public function save_supplier($id = NULL)
	{
		$data   = array(
			'sup_account'		=> $this->input->post('sup_account'),
			'sup_name'			=> $this->input->post('sup_name'),
			'ftp_host'			=> $this->input->post('ftp_host'),
			'ftp_port'			=> $this->input->post('ftp_port'),
			'ftp_user'			=> $this->input->post('ftp_user'),
			'ftp_pass'			=> $this->input->post('ftp_pass'),
			'ftp_directory'		=> $this->input->post('ftp_directory'),
			'comp_file'			=> $this->input->post('comp_file'),
			'uncomp_file'		=> $this->input->post('uncomp_file'),
			'feed_separator'	=> $this->input->post('feed_separator'),
			'n_ftp_directory'	=> $this->input->post('n_ftp_directory'),
			'n_comp_file'		=> $this->input->post('n_comp_file'),
			'n_uncomp_file'		=> $this->input->post('n_uncomp_file'),
			'n_feed_separator'	=> $this->input->post('n_feed_separator'),
			'date_format'		=> $this->input->post('date_format')
        );
		
		if ($id)
		{
			return $this->update($id, $data);
		}
		else
		{
			return $this->insert($data);
		}
	}      
	
	public function search()
	{
		if ($this->input->post('submit'))
		{
			if ($this->form_validation->run($this, 'search_feeds') !== FALSE)
			{
				$this->set_table(FALSE);
				$query = $this->find_all_by('id', 1);
				$this->set_table();
				return $query;
			}
		}
		else
		{
			return NULL;
		}
	}
	
	/**
	 * Set table method for multiple tables in model
	 * @link http://blog.s-vizion.com/2012/codeigniter/a-quick-tip-on-codeigniter-and-bonfires-model-for-evil/
	 * @param boolean $table Set primary or alt table
	 * @return \Suppliers_model 
	 */
	public function set_table ($table = TRUE)
	{
		if ($table === TRUE)
		{
			$this->table = 'bf_supplier_details';
			$this->key   = 'id';
		} else {
			$this->table = $this->alt_table;
			$this->key   = $this->alt_key;
		}

		return $this;
	}
}