.....       
       CASE 
            WHEN Invoice.BlockUnblock = 1 THEN 'CLIENT'
            WHEN Invoice.Dispute = 'Dispuut' THEN 'CLIENT'
            ELSE 'CF'
       END                     AS ActieLigtBij,
       t2.[Description]
FROM   Debtor
       INNER JOIN Client
            ON  Debtor.ClientNr = Client.ClientNr
       INNER JOIN Invoice
            ON  Debtor.ClientNr = Invoice.ClientNr
            AND Debtor.DebtorNr = Invoice.DebtorNr
       LEFT OUTER JOIN (
                SELECT ClientNr,
                       DebtorNr,
                       TextFree
                FROM   Dispute
            )                  AS Dispuuttekst
            ON  Debtor.ClientNr = Dispuuttekst.ClientNr
            AND Debtor.DebtorNr = Dispuuttekst.DebtorNr
       OUTER APPLY
       (
       		SELECT TOP (1)
       			idLog,
				Clientnr,
				Debtornr,
				ActivityDate,
				ActivityTime,
				DESCRIPTION
       		FROM
       			Table2 t2
       		WHERE 
       			t2.Debtornr = Debtor.DebtorNr
       			AND t2.ClientNr = Debtor.ClientNr
       		ORDER BY
       			ActivityDate DESC,
       			idlog DESC
       ) t2
       			
WHERE  (
           Client.ClientNr = 5267
           OR Client.ClientNr = 5395
           OR Client.ClientNr = 5292
       )
.....

SELECT *
FROM
(
SELECT Client.ClientNr AS Klantnr, Client.ClientName AS Klantnaam, Debtor.DebtorNr AS Debiteurnr, Debtor.DebtorName AS DebiteurNaam, 
Invoice.InvoiceNr AS Factuurnr, Invoice.InvoiceDate AS FactuurDatum, Invoice.VervalDatum AS Vervaldatum, Invoice.OpenstaandBedrag, 
Invoice.DaysOpen AS DagenVervallen, CASE WHEN Invoice.BlockUnblock = 1 THEN 'JA' ELSE 'NEE' END AS GeblokkeerdJN, 
Invoice.InvoiceBlocked AS BlokkeerOmschrijving, CASE WHEN Invoice.Dispute = 'Dispuut' THEN 'JA' ELSE 'NEE' END AS DispuutJN, 
CASE WHEN Invoice.Dispute = 'Dispuut' THEN Dispuuttekst.TextFree ELSE 'nvt' END AS DispuutOmschrijving, 
CASE WHEN Invoice.BlockUnblock = 1 THEN 'CLIENT' WHEN Invoice.Dispute = 'Dispuut' THEN 'CLIENT' ELSE 'CF' END AS ActieLigtBij
FROM Debtor INNER JOIN
Client ON Debtor.ClientNr = Client.ClientNr INNER JOIN
Invoice ON Debtor.ClientNr = Invoice.ClientNr AND Debtor.DebtorNr = Invoice.DebtorNr LEFT OUTER JOIN
(SELECT ClientNr, DebtorNr, TextFree
FROM Dispute) AS Dispuuttekst ON Debtor.ClientNr = Dispuuttekst.ClientNr AND Debtor.DebtorNr = Dispuuttekst.DebtorNr
WHERE (Client.ClientNr = 5267 OR
Client.ClientNr = 5395 OR
Client.ClientNr = 5292) AND (Invoice.OpenstaandBedrag <> 0) AND (Invoice.DaysOpen > 0) AND (Invoice.DaysOpen > 30)
)p
INNER JOIN
(
SELECT ROW_NUMBER() OVER (PARTITION BY ClientNr,DebtorNr ORDER BY ActivityDate DESC) AS Seq,
ClientNr,
DebtorNr,
ActivityDate,
ActivityTime,
Administrator,
ActivityType,
Description,
AgendaDate,
AgendaAction,
AgendaDescription,
Subject,
Type,
IdLog
FROM
LogFile
WHERE
Service = 'OUT'
AND type = 'Activity'
AND ActivityType <> ''
AND Activitytype <> 'specdeb'
)q
ON q.Seq=1
AND q.ClientNr = p.Klantnr
AND q.DebtorNr = p.Debiteurnr
ORDER BY DebiteurNaam