Selecting Between Dates Getting More Rows?

I have two tables a stock table and a price table and I want to select the correct price for the Stock Date.

Problem is sometimes there is a promotion date in the price table between the live dates so the rows double up. Below is my sql but I get over 17,000 rows when it should be about 16,964.

I will post up the table and data.

SELECT a.[Company]
,a.[ProductID]
,a.[ColourSize]
,a.[StockDate]
,a.[Quantity]
,b.[Ticket Price]
FROM[Stock_Ledger] a
LEFT OUTER JOIN [Product_Prices] b
ON a.[Company] = b.[Company]
AND a.[ProductID] = b.[ProductID]
AND a.[ColourSize] = b.[ColourSize]
AND a.[StockDate] BETWEEN b.[StartDate] AND b.[EndDate]
ORDER BY a.[StockDate],a.[ProductID],a.[ColourSize]