"Ya se ha agregado un elemento con la misma clave" Error en SSRS al intentar establecer un conjunto de datos

Cuando intento configurar el conjunto de datos en SSRS IDE, aparece el error que ves en la instantánea.

La consulta funciona totalmente bien en SQL Server Management Studio, me pregunto dónde me equivoqué.

La conexión a DB está bien establecida.

OPCIONAL:

En caso de que quiera ver mi consulta (es demasiado larga), la revisé muy bien. No hay nada malo en ello:

SELECT Customer.customerID, Customer.companyName,  CustomerInvoice.dueDate, CustomerInvoice.cuInvoiceID, CustomerQuote.PONumber, Product.productName, CASE WHEN (SELECT     isTaxPaid
                                                     FROM         SupplierQuoteProducts
                                                     WHERE     productID = CustomerQuoteProducts.ProductID) = 1 THEN CustomerQuoteProducts.unitPrice * 1.15
                                                     WHEN (SELECT     isTaxPaid
                                                     FROM         SupplierQuoteProducts
                                                     WHERE     productID = CustomerQuoteProducts.ProductID) = 0 THEN CustomerQuoteProducts.unitPrice
                                                     ELSE CustomerQuoteProducts.unitPrice
                                                     END AS "unitPrice", 
                      CustomerQuoteProducts.qty, CustomerQuoteProducts.isTaxPaid, PaymentMethod.paymMethDesc, CustomerInvoice.customerQuoteID, CustomerInvDetail.paidDate, CustomerInvDetail.clearedDate,
                      CustomerInvDetail.notes, CustomerInvDetail.sentDate, PaymentExpected.payExpectedTitle, PaymentStatus.paymentStatusTitle, 
CASE WHEN
(SELECT     isTaxPaid
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 1 AND CustomerQuoteProducts.qty > 0 AND 
CustomerQuoteProducts.isTaxPaid > 0 THEN (((CustomerQuoteProducts.unitPrice * 1.15) * 1.15) * CustomerQuoteProducts.qty) WHEN
(SELECT     isTaxPaid
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 1 AND CustomerQuoteProducts.qty <= 0 AND 
CustomerQuoteProducts.isTaxPaid > 0 THEN ((CustomerQuoteProducts.unitPrice * 1.15) * 1.15) WHEN
(SELECT     isTaxPaid
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 0 AND CustomerQuoteProducts.qty > 0 AND 
CustomerQuoteProducts.isTaxPaid > 0 THEN ((CustomerQuoteProducts.unitPrice * CustomerQuoteProducts.qty) * 1.15) WHEN
(SELECT     isTaxPaid
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 0 AND CustomerQuoteProducts.qty <= 0 AND 
CustomerQuoteProducts.isTaxPaid > 0 THEN (CustomerQuoteProducts.unitPrice * 1.15) WHEN
(SELECT     Count(isTaxPaid)
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 0 AND CustomerQuoteProducts.qty > 0 AND 
CustomerQuoteProducts.isTaxPaid > 0 THEN ((CustomerQuoteProducts.unitPrice * 1.15) * CustomerQuoteProducts.qty) WHEN
(SELECT     Count(isTaxPaid)
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 0 AND CustomerQuoteProducts.qty <= 0 AND 
CustomerQuoteProducts.isTaxPaid > 0 THEN (CustomerQuoteProducts.unitPrice * 1.15) WHEN
(SELECT     isTaxPaid
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 1 AND CustomerQuoteProducts.qty > 0 AND 
CustomerQuoteProducts.isTaxPaid <= 0 THEN (((CustomerQuoteProducts.unitPrice * 1.15)) * CustomerQuoteProducts.qty) WHEN
(SELECT     isTaxPaid
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 1 AND CustomerQuoteProducts.qty <= 0 AND 
CustomerQuoteProducts.isTaxPaid <= 0 THEN ((CustomerQuoteProducts.unitPrice * 1.15)) WHEN
(SELECT     isTaxPaid
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 0 AND CustomerQuoteProducts.qty > 0 AND 
CustomerQuoteProducts.isTaxPaid <= 0 THEN ((CustomerQuoteProducts.unitPrice * CustomerQuoteProducts.qty)) WHEN
(SELECT     isTaxPaid
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 0 AND CustomerQuoteProducts.qty <= 0 AND 
CustomerQuoteProducts.isTaxPaid <= 0 THEN (CustomerQuoteProducts.unitPrice) WHEN
(SELECT     Count(isTaxPaid)
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 0 AND CustomerQuoteProducts.qty > 0 AND 
CustomerQuoteProducts.isTaxPaid <= 0 THEN ((CustomerQuoteProducts.unitPrice * CustomerQuoteProducts.qty)) WHEN
(SELECT     Count(isTaxPaid)
 FROM         SupplierQuoteProducts
 WHERE     productID = CustomerQuoteProducts.ProductID) = 0 AND CustomerQuoteProducts.qty <= 0 AND 
CustomerQuoteProducts.isTaxPaid <= 0 THEN (CustomerQuoteProducts.unitPrice) END AS [TotalPrice], CASE WHEN row_number() OVER (partition BY 
CustomerInvoice.cuInvoiceId
ORDER BY newid()) = 1 THEN (CASE WHEN CustomerShipping.isTaxPaid > 0 THEN (CustomerShipping.shippingPrice * 1.15) 
WHEN CustomerShipping.isTaxPaid <= 0 THEN (CustomerShipping.shippingPrice) END) END AS [ShippingCost],
CASE WHEN row_number() OVER (partition BY 
CustomerInvoice.cuInvoiceId
ORDER BY newid()) = 1 THEN (CASE WHEN CustomerShipping.isTaxPaidForOrigPr > 0 THEN (CustomerShipping.origShipPrice * 1.15) 
WHEN CustomerShipping.isTaxPaidForOrigPr <= 0 THEN (CustomerShipping.origShipPrice) END) END AS [ShippingOrigCost],
CustomerShipping.isTaxPaid,
CustomerShipping.isTaxPaidForOrigPr,
CustomerShipping.shippingDate, CustomerShipping.trackingNumber, ShippingMethod.shippingVia, CustomerShipping.desAddress,
CustomerShipping.desCity, CustomerShipping.desPOBox, CustomerShipping.desPostalCode, CustomerShipping.desProvince, CustomerShipping.descName,
CustomerShipping.packageContent, CustomerShipping.cuShippingID, Country.countryName, CustomerShipping.packageDepth,
CustomerShipping.packageHeight, CustomerShipping.packageWeight, CustomerShipping.packageWidth, CustomerShipping.pickUpLocation
FROM         CustomerInvoice INNER JOIN
                      CustomerInvDetail ON CustomerInvoice.cuInvoiceID = CustomerInvDetail.cuInvoiceID INNER JOIN
                      CustomerQuote ON CustomerQuote.CustomerQuoteID = CustomerInvoice.CustomerQuoteID INNER JOIN
                      CustomerQuoteProducts ON CustomerQuoteProducts.CustomerQuoteID = CustomerQuote.CustomerQuoteID INNER JOIN
                      CustomerShipping ON CustomerShipping.CustomerQuoteID = CustomerInvoice.CustomerQuoteID INNER JOIN
                      PaymentStatus ON PaymentStatus.paymentStatusID = CustomerInvDetail.paymentStatusID INNER JOIN
                      Customer ON Customer.CustomerID = CustomerQuote.CustomerID INNER JOIN
                      Product ON CustomerQuoteProducts.productID = Product.productID INNER JOIN
                      Country ON Country.countryID = CustomerShipping.countryID INNER JOIN
                      ShippingMethod ON ShippingMethod.shippingMethodID = CustomerShipping.shippingMethodID INNER JOIN
                      PaymentExpected ON PaymentExpected.paymentExpectedID = CustomerInvDetail.paymentExpectedID INNER JOIN
                      PaymentMethod ON PaymentMethod.paymentMethodID = CustomerInvoice.paymentMethodID
WHERE  CustomerInvoice.cuInvoiceID = @cuInvID