Mysql left join does not work

I want to get total transfered items from table inv_site_item where 'item_id' in inv_sie_item = 'item_code' in inv_items, I am getting packing also from packing table which works fine in this query only inv_site_item is giving problem.

error is: Unknown column 'inv_site_item.site_id' in 'field list'

$where .= " AND inv_items.item_code = $item_code";

$query = "SELECT inv_items.*,packing.name_en `packing_name`,"
    . " COUNT(inv_site_item.site_id) `transfer_out`, COUNT(inv_site_item.location_site_id) `transfer_in`  FROM inv_items"
            . " left join "
            . "inv_packing as packing on packing.id=inv_items.packing"
            . " left join "
            . "inv_site_item as transfer on transfer.item_id=inv_items.item_code"
    . " WHERE item_code !='' " . $where . "";

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you must use your table alias transfer instead, So:

change from

inv_site_item.site_id

to

transfer.site_id

also with inv_site_item.location_site_id to be transfer.location_site_id