SQL 2012 :: Using OVER Command Together With (WITH) And Excel With A Parameter?

I'm am using an Excel with a parameter, in this case a customer-number. For retrieving the data I use a view. In this view I start with a WITH to retrieve the data because I need the customer number in several places in the view. In the beginning all data I need is a 1:1 relation with the customer but problems occurs when there is a 1:n relation, in my case a customer can have more contact persons. When I try to collect the contact person information it always finds the first contact person in the table and that's from a different customer.

What do I have to do to find the contact person(s) that belongs to my specific customer/?

with Customer as (
Select * from [ods].[custtable] where ODSACTIVE = '1' AND DATAAREAID = 'NL01'
)
union all
select src.accountnum, 'Contact Person 1 Name' as 'Field', SRC.NAME as 'Value'
FROM (SELECT CP.NAME, CT.accountnum, ROW_NUMBER() OVER (ORDER BY CP.PARTYID) AS RN, ct.partyid
from [ods].[contactperson] cp inner join CUSTOMER CT on ct.partyid = cp.ORGpartyid and ct.DATAAREAID = cp.DATAAREAID
WHERE cp.DATAAREAID = 'NL01'
) AS SRC WHERE SRC.RN = 1