AJAX :: Exception Error With Slideshow Service

I have the following problem with a slideshow in Ajax. Hope I have put it in the right Ajax forum. Some info: I do use MS Access and in the 'autos table' i do have the following fields:

field 1: nummer (text field) - this is the name of the image
field 2: cat (integer) - this is the category of the cars
field 3: naam (text field) - this is the name of the car
field 4: model (text field - this is the model of the car

In my masterpage i do have a menu where you can make the choice of a certain category of cars. This is done by a call to: slideshow.aspx?cat=100 In Slideshow.aspx a panel is setup and also buttons to manipulate the found images. Also the AjaxToolkit:Slideshowextender is defined as follows:

<ajaxToolkit:SlideShowExtender ID="SlideShowExtender1" runat="server"
TargetControlID="Image1"
SlideShowServicePath="slideservice.asmx"
SlideShowServiceMethod="Getslides"
AutoPlay="true"
ImageTitleLabelID="Name"
ImageDescriptionLabelID="Desc"
NextButtonID="NextButton"
PlayButtonID="PlayButton"
PlayButtonText="Play"
StopButtonText="Stop"
PreviousButtonID="PrevButton"
PlayInterval="4000"
Loop="true"
ContextKey="catid" />
As you can see the contactkey is also defined.
Inside the codebehind of slideshow.aspx.vb their is a sub defined:
Partial Class Slideshow
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
SlideShowExtender1.ContextKey = Request.QueryString("catid")
End Sub
End Class
The call from slideshow.aspx is to a slideservice.asmx which contains:
<%@ WebService Language="VB" CodeBehind="~/App_Code/SlideService.vb" %>
Here we call slideservice.vb.
The coding of the slideservice.vb file is:
Imports System.Web
Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.Data.OleDb
Imports System.Web.UI.Page
<WebService(Namespace:="http://vancouver.com/")> _
<WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _
<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
<System.Web.Script.Services.ScriptService()> _
Public Class SlideService
Inherits System.Web.Services.WebService
<WebMethod()> _
Public Function GetSlides(ByVal contextKey As String) As AjaxControlToolkit.Slide()
Dim strconn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|Vancouver.mdb"
Dim cn As New OleDbConnection(strconn)
Dim SQLStr As String
SQLStr = "SELECT nummer, naam, model FROM Autos WHERE ((Autos.cat) = @catid)"
Try
cn.Open()
Dim cmd As New OleDbCommand(SQLStr, cn)
Dim sCatid As String = ""
' Give the value to sCatid from contextkey
If sCatid.Trim().Length = 0 Then sCatid = contextKey
cmd.Parameters.AddWithValue("@catid", sCatid)
Dim thisReader As OleDbDataReader = cmd.ExecuteReader()
Dim photoCounter As Integer
While thisReader.Read()
photoCounter = photoCounter + 1
End While
If (photoCounter > 0) Then
'we now know how many pictures there are in this category of the database
Dim MySlides(photoCounter - 1) As AjaxControlToolkit.Slide
'set up the command string
Dim photoLookupCmd As New OleDbCommand(SQLStr, cn)
'and add the parameters to it for the category
photoLookupCmd.Parameters.AddWithValue("@catid", sCatid)
thisReader = photoLookupCmd.ExecuteReader()
Dim i As Integer
For i = 0 To photoCounter - 1
thisReader.Read()
Dim number As String = thisReader.GetString(0)
Dim name As String = thisReader.GetString(1) + " - " + thisReader.GetString(2)
MySlides(i) = New AjaxControlToolkit.Slide(("pictures" + number + ".jpg"), name, "")
Next
thisReader.Close()
Return MySlides
Else
Dim MySlides(0) As AjaxControlToolkit.Slide
MySlides(0) = New AjaxControlToolkit.Slide("pictures99999.jpg", "sorry - not available", "pls. mail us to report")
thisReader.Close()
Return MySlides
End If
Catch x As Exception
Dim MySlides(0) As AjaxControlToolkit.Slide
MySlides(0) = New AjaxControlToolkit.Slide("pictures99999.jpg", "Exception error", "pls. mail us to report")
Return MySlides
Finally
cn.Close()
End Try
End Function
End Class

When i run the code i will get an exception error and when following the code in debug mode i do see that inside the first loop in FOR i = 0 to photocounter - 1 : The first loop gets the right info from the database inside Myslide(1) fields. Going into the second loop i will get after dim name as string .....

the program goes to catch x as exception. I did see that number was found correctly during the previuous line. During an other debug session i noticed that the Parameter.item has the following error (which I do not understand), saying: Overload resolution failed because no accessible 'Item´ accepts this number of arguments.