POST METHOD Sales Order Bad Request 400

Hi , I have a problem , when i send a post request to sales order it give me 400 error
here it is :
http://localhost:8000/api/method/onlinestore.www.shopcart.addToShopcart Failed to load resource: the server responded with a status of 400 (BAD REQUEST)
http://localhost:8000/api/method/onlinestore.www.shopcart.addToShopcart XHR finished loading: POST “http://localhost:8000/api/method/onlinestore.www.shopcart.addToShopcart”.

when i press on the link i see that my code works find and i see the message i set for which is : {“message”:“done”}

here’s my python method :

def addToShopcart():
item = frappe.get_list(“Item”, “*”, filters={“item_code”: “02”})
if item:

    price = "22"
    ss = frappe.get_doc({
        "doctype": "Sales Order",
        "delivery_date": "05 - 12 - 2016",
        "transaction_date": "05-12-2016",
        "customer": "Yussuf",
        "items": [{"item_code": item[0].item_code,
                   "item_name": item[0].item_name,
                   "description": item[0].description,
                   "price": price}]
    return "done"
    msg = "No such item available"
    return msg

any suggesting .??

i test the data with POSTMAN and it works and add with the API/RESOURCE/SALES ORDER
i need it to work with my method




can you share the error traceback ?

Thanks, Makarand