Remove Duplicate Records From Left Join - sql-server-2014

Question

I work with Microsoft Dynamics Navision 2013 and SQL 2014 as the data source. The Value entry table is the main table that host all sales transaction for customers / Items.
For some of the items we pay Excise (Tax), a certain rate we pay for all items being transferred from one warehouse to another which we call (Transfer Excise).
I work for a wine farm and for each year we enter a unit rate for each item per location(Location being the warehouse where the wine is stored before transfer out of the warehouse]. Our unit rate was created on the 28-02-28.
In order to get the calculation for the Transfer Excise I took data from various tables from Microsoft Dynamics Navision. The tables are containing the columns I took:
Location : Code, also contains a filter “NONBOND”
Item: No(PK) , Excise Type
Excise Rate: Starting Date (The starting date of the Unit Rate), Excise Type Code
Item Unit Of Measure: Item No(PK), Qty_ per unit of measure as (Litre Conversion Factor)
The data was entered into a new table called Transfer Excise Tbl 1. To simplify my example, my Transfer Excise table contains: No_ and Location Code (FK) my Value Entry Table contains Item No_(PK) , Location Code(PK). Of course I will join Transfer Excise and Value Entry table on (No_=Item No_) and Location code = Location code.
I'm trying to get all item transactions which match the Value Entry table for each unit rate for that specific starting date and the posting date when the transaction were posted using LEFT JOIN with filters.
In the Value Entry table I use Gen_ Bus_ Posting Group to filter only (LOCA & EXSA), LOCA meaning local and EXSA meaning Export South Africa. This is the query I am trying, however I get duplicates with no starting dates and posting dates. I tried using DISTINCT as seen in my query but it does not work.
SELECT DISTINCT a.[Starting Date],
b.[Posting Date],
b.[Item No_],
b.[Invoiced Quantity],
a.[Litre Conversion Factor],
a.[Unit Rate] ,
a.[Location Code],
a.[Excise Location],
a.[Excise Type Code],
a.[Unit Of Measure Code]
FROM [Transfer Excise Tbl] a
LEFT JOIN [Spier Live$Value Entry] b
ON a.[No_] = b.[Item No_]
WHERE b.[Posting Date] > '2014-03-01'
AND b.[Item No_] = 'F00335'
AND b.[Location Code] = a.[Location Code]
AND b.[Gen_ Bus_ Posting Group] IN ('LOCA','EXSA')
AND b.[Posting Date] >= a.[Starting Date]
AND b.[Invoiced Quantity] <>0
order by b.[Posting Date]