How to run trigger for each affected row in delete query

Hello every body, can anyone help me ?

I will describe my problem. First, i have 2 table name tbStock andtbSalesDetail. Column in tbStock and tbSalesDetail is like this :

CREATE TABLE tbStock (
	idStock INT PRIMARY KEY,
	nameStock VARCHAR(250) NOT NULL,
	qtyStock FLOAT NOT NULL
);
GO
INSERT INTO tbStock (idStock, nameStock, qtyStock) VALUES (0, 'Apple', 100);
INSERT INTO tbStock (idStock, nameStock, qtyStock) VALUES (1, 'Banana', 80);
GO
CREATE TABLE tbSalesDetail (
	idData BIGINT IDENTITY(0,1) PRIMARY KEY,
	invoiceNumber VARCHAR(20) NOT NULL,
	idStock INT NOT NULL,
	qtySales FLOAT NOT NULL
);
GO
INSERT INTO tbSalesDetail (invoiceNumber,idStock,qtySales) VALUES ('JL001',0,10);
INSERT INTO tbSalesDetail (invoiceNumber,idStock,qtySales) VALUES ('JL001',1,5);
GO

Then, i want to update qtyStock in tbStock when data insert into tbSalesDetail or delete from tbSalesDetail with trigger. (In this case, i use delete from tbSalesDetail). So, i create trigger like this :

CREATE TRIGGER tbSalesDetail_Trigger_Delete ON tbSalesDetail
FOR DELETE
AS
BEGIN
	DECLARE @idStockX INT, @qtySalesX FLOAT;
	SELECT @idStockX=idStock, @qtySalesX=qtySales FROM deleted;
	UPDATE tbStock SET qtyStock=qtyStock+@qtySalesX WHERE idStock=@idStockX;
END
GO

The trigger is run. I hope if i run delete command like :

DELETE FROM tbSalesDetail WHERE invoiceNumber='JL001';

will make the quantity of stock become like this :

Product Apple (idStock=0) = 100+10=110

Product Banana (idStock=1) = 80+5=85

But in the fact, Quantity Apple is True (110) and Quantity Banana isFalse (still 80).

I know this problem because trigger only run for first row. So how can i update each data in affected row with trigger ? (I use Windows 7 SP1 32 bit and SQL Server 2012 SP1 Express Edition)