I'm trying to add product_id.description_picking to stock.pack.operation(pack_operation_product_ids)

#Form view

<record id="view_stock_picking_form" model="ir.ui.view">

    <field name="name">Stock Picking Price Form</field>
    <field name="model">stock.picking</field>
    <field name="inherit_id" ref="stock.view_picking_form"/>
    <field name="arch" type="xml">
        <xpath expr="//page/field[@name='pack_operation_product_ids']/tree/field[@name='product_id']" position="after">
            <field name="description_picking"/>
        </xpath>
    </field>
</record>

#Model

class descmoduledo(models.Model):
    _inherit ='stock.picking'
#
    description_picking = fields.Char(string='Picking Description',store=True,related='product_id.descriptio_picking')

class StockPackOperation(models.Model):
    _inherit ='stock.pack.operation'
    description_picking = fields.Char(string='Picking Description',store=True,related='product_id.description_picking')

when i install my module it show error 
raise 

TypeError("Type of related field %s is inconsistent with %s" % (self, field))
TypeError: Type of related field stock.pack.operation.description_picking is inconsistent with product.product.description_picking