Why does not the insert work? This inserts the data from the checkin table linked with INNER JOIN to the client table by the document key

Why does not the insert work? This inserts the data from the checkin table linked with INNER JOIN to the client table by the document key and the hosting table with the id_location key, thank you very much for the help that you can provide.

$insertar=("INSERT into a.id_che,a.checkin,a.checkout,a.documento,a.id_alojamiento
      SELECT a.*,b.*,c.*
      FROM checkin AS a
      INNER JOIN huesped AS b ON a.documento=b.documento
      INNER JOIN alojamiento AS c ON c.id_aloja=a.id_alojamiento 
      VALUES (NULL,$checkin,$checkout,$doc,$id_a)
      WHERE b.documento=$doc,c.id_aloja=$id_a");