Error creating complex Function in SQL Server

Hello there,

I am trying to create a function in mssql 2012 database and for some reason I get this error. The main query which I am trting to insert in the table variable is running perfectly on its own but when I try to put it in a function,it breaks..

1) [Error Code: 156, SQL State: S1000]  Incorrect syntax near the keyword 'with'. 2) [Error Code: 319, SQL State: S1000]  Incorrect syntax near the keyword 'with'. If this statement is a common table expression, an xmlnamespaces clause or a change tracking context clause, the previous statement must be terminated with a semicolon.

CREATE FUNCTION ProductSaleReturnNDiscountByProvince ( @receiptStartDate datetime, @receiptEndDate datetime ) 
RETURNS  
   @ProductSaleReturnNDiscountByProvince TABLE ( 
       [ProductCode] [nchar] (15),  
       [ProductName] [nvarchar] (300),  
       [Province] [nvarchar] (50),  
       [SalesReturnQty] BigInt ,  
       [SalesReturnDiscount] BigInt 
   ) 
AS 
BEGIN 

INSERT INTO @ProductSaleReturnNDiscountByProvince  
with q as (
SELECT
    RIGHT('000' + CAST(kol.code AS VARCHAR), 3) + RIGHT('00'+ CONVERT(VARCHAR,dbo.Mohin.code),3) + '' +  RIGHT('0000' + CAST(tafsil.code AS VARCHAR), 4) AS ProductCode,
    dbo.Province.name AS Province,
     SUM(dbo.SaleReturnDetail.quantity) AS SalesReturnQty,
    dbo.Tafsil.description as ProductName,
    (CASE 
     WHEN (dbo.SaleDetail.type = 0 ) THEN 'Sales'
                                            ELSE 'Discount' 
 END) as SaleType
FROM
    dbo.Sale
INNER JOIN
    dbo.DeliveryOrder
ON
    (
        dbo.Sale.orderId = dbo.DeliveryOrder.id)
INNER JOIN
    dbo.Customer
ON
    (
        dbo.DeliveryOrder.customerId = dbo.Customer.id)
INNER JOIN
    dbo.SaleReturn
ON
    (
        dbo.Sale.id = dbo.SaleReturn.saleId)
INNER JOIN
    dbo.ContactInformation
ON
    (
        dbo.Customer.organizationContactInformationId = dbo.ContactInformation.id)
INNER JOIN
    dbo.Address
ON
    (
        dbo.ContactInformation.addressId = dbo.Address.id)
INNER JOIN
    dbo.City
ON
    (
        dbo.Address.cityId = dbo.City.id)
INNER JOIN
    dbo.District
ON
    (
        dbo.City.districtId = dbo.District.id)
INNER JOIN
    dbo.Province
ON
    (
        dbo.District.provinceId = dbo.Province.id)
INNER JOIN
    dbo.SaleReturnDetail
ON
    (
        dbo.SaleReturn.id = dbo.SaleReturnDetail.saleReturnId)
INNER JOIN
    dbo.Batch Batch_alias1
ON
    (
        dbo.SaleReturnDetail.batchId = Batch_alias1.id)
INNER JOIN
    dbo.Receipt
ON
    (
        dbo.SaleReturn.invoiceReceiptId = dbo.Receipt.id)
INNER JOIN
    dbo.Tafsil
ON
    (
        Batch_alias1.productId = dbo.Tafsil.id)
INNER JOIN
    dbo.Mohin
ON
    (
        dbo.Tafsil.mohinId = dbo.Mohin.id)
INNER JOIN
    dbo.Kol
ON
    (
        dbo.Mohin.kolId = dbo.Kol.id)
        INNER JOIN
    dbo.SaleDetail
ON
    (
        dbo.SaleReturnDetail.saleDetailId = dbo.SaleDetail.id)
WHERE
    dbo.Receipt.receiptDate >= @receiptStartDate
AND dbo.Receipt.receiptDate < @receiptEndDate
GROUP BY
    dbo.SaleDetail.type,
    dbo.Tafsil.description,
    dbo.Province.name,
    kol.code,
    Mohin.code,
    Tafsil.code)
 select q1.ProductCode,
q1.ProductName,
q1.Province,
q1.SalesReturnQty AS salesReturn,
q2.SalesReturnQty AS discountReturn
FROM q as q1 INNER JOIN q as q2
ON q1.ProductCode =  q2.ProductCode
 AND q1.ProductName = q2.ProductName
 AND q1.Province = q2.Province
 AND q1.SaleType = 'Sales' AND q2.SaleType = 'Discount'
    
   RETURN 
END

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Can somebody please help me resolve this error.

cheers
Zolf