my problem got solved by adding this code in  action_wait:

 order_line_ids = self.pool.get('sale.order.line').search(cr, uid, [('order_id', '=', o.id)])
            for so_line in self.pool.get('sale.order.line').browse(cr, uid, order_line_ids):
                  so_line_id = self.pool.get('product.product').search(cr, uid, [('id', '=', so_line.product_id.id)])
                  for bom in self.pool.get('mrp.bom').browse(cr, uid, so_line_id):   
                      xbom_id = self.pool.get('mrp.bom').search(cr, uid, [('product_id', '=', bom.id)]
                      for child_bom in self.pool.get('mrp.bom').browse(cr,uid,xbom_id):
                          child_bom_ids = self.pool.get('mrp.bom').search(cr,uid,[('id','=',child_bom.id)]
                          if (child_bom.product_id > child_bom.product_id.qty_available):  
                                raise osv.except_osv(_('Not enough Stock !'), _('You requested %.2f.The available Components is %s !') %(child_bom.product_qty, child_bom.product_id.qty_available))