Cannot find the Nvarchar to Int conversion in my code
<p>I am currently making a project for school where I have to make a program where I can create orders in.
When I try to create orders I get this error returned to me.</p>

<p>Error converting Data Type Nvarchar to Int.</p>

<p>In advance I'm sorry if this is a really basic question that is easely spotted. Me and my project members are beginning programmers but we simply cannot spot where this goes wrong.</p>

<p>The code we execute in vba is this :</p>

<pre><code>Set rs = DbConn.Execute("EXEC spOrderPlaatsen '" &amp; Me.tbTijd &amp; "', " &amp; Me.klantnr &amp; ", '" &amp; Me.tbOphaaldatum &amp; "', '" &amp; Me.tbAfleverdatum &amp; "', '" &amp; Me.tbOphaaladres &amp; "', " &amp; Me.tbPalletnr &amp; ", " &amp; Me.tbAantalpallets &amp; "")
</code></pre>

<p>This code execute's our Stored procedure.
The stored procedure looks like this.</p>

<pre><code>CREATE PROCEDURE spOrderPlaatsen
(  
@tijd               time(0),
@klantnr            integer,
@ophaaldatum        date,
@afleverdatum       date,

@palletnr   integer,
@aantal     integer,
@Adres      Varchar(255)

) 
AS 

BEGIN TRANSACTION 

DECLARE @ordernr int
DECLARE @besteldatum date

set @besteldatum = getdate()

SELECT @ordernr = MAX(o.ordernr) + 1 
FROM orders o 

insert into orders values (@ordernr, @besteldatum, @tijd, @klantnr, @ophaaldatum, @afleverdatum, @adres)
insert into orderregel values (@ordernr, @palletnr, @aantal)

IF @@ERROR &lt;&gt; 0 
BEGIN 

ROLLBACK 

RAISERROR ('Error tijdens het plaatsen van order.', 16, 1) 
RETURN 
END 

COMMIT
go
</code></pre>

<p>Somehow we get a conversion error that we cannot find.</p>

<p>Could any1 figure this out for us? It would be greatly appreciated</p>