Crystal Reports Duplicated Rows?

Message

     Hello, Hope someone can help quickly :(

I am using 2 tables: TRANSACTIONS & VANRUNS

TRANSACTIONS obviously contains all the transaction details

VANRUNS contains: CUSTOMER, NAME, VANRUN & VANDESCRIPTION

linking: TRANSACTIONS  > Left outer > VANRUNS

each customer can have upto 3 different van runs on the account (I think this is where the problem is)

I am grouping by {TRANSACTIONS.CUSTOMER}

then in details showing; INVOICE# , INVOICEDATE , QUANTITY

which is great.  It returns data like;

CUSTOMER ABC
INV123456    04/04/2012     24 units
INV345687    07/04/2012     21 units

When I add a Select Expert Filter on the the VANRUNS.VANRUN field, this is when the duplications start.

ie;  VANRUNS.VANRUN is one of 319, 320  I get data like;

CUSTOMER ABC
INV123456    04/04/2012     24 units
INV123456    04/04/2012     24 units
INV345687    07/04/2012     21 units
INV345687    07/04/2012     21 units

If I remove one of the vanruns, so its VANRUNS.VANRUN =319 It does not duplicate the data. It only duplicates when I include more than 1 vanrun in the select expert.

Any ideas?

Thanks.