PageMethodes is not always called after upgraded to IE9

HI all,

The app works fine in IE8. When upgraded to IE9, the problem is appears. The code is not changed.

In the javascript there is a function which calls a server side subroutine with parameter. The problem is: Sometime the subroutine is performed, somethime not, even the parameter/data is the same.

What I have doen is:

-Add the site as a trusted side in Internet Options/Security

-Add this in the header of the aspx file.: <meta http-equiv="X-UA-Compatible" content="IE=8" />

but it doesn't work, same problem: sometime works, sometime not.

Here is the javascript in aspx file:

function IsOK()
{
//alert("in isOK.")

   var erro = '';
   var MasterID = document.getElementById('<%= hid_masterID.ClientID %>').value;
   var IID = document.getElementById('<%= hid_ID.ClientID %>').value;
   var PostID = document.getElementById('<%= ddlGemeente.ClientID %>').value;
   var FunctieID = document.getElementById('<%= ddlFunction.ClientID %>').value;
   var StatusID = document.getElementById('<%= ddlNewStatus.ClientID %>').value;
   var ResultaatID = document.getElementById('<%= ddlResultaat.ClientID %>').value;
   //alert("now goes to server side.")
   PageMethods.saveData(MasterID, IID, PostID, FunctieID, StatusID, ResultaatID);
}

In aspx I have ScriptManager like this:

<asp:ToolkitScriptManager ID="tsmanager" runat="server" ScriptMode="Release" EnablePageMethods="True"></asp:ToolkitScriptManager>

In the server side (aspx.vb):

<System.Web.Services.WebMethod()> _
Public Shared Sub saveData(ByVal MasterID As Integer, ByVal IID As Integer, ByVal PostID As Integer, ByVal FunctieID As Integer, ByVal StatusID As Integer, ByVal ResultaatID As Integer)
   Dim cn As New SqlConnection
   Dim cmd As New SqlCommand
   Dim conn As New SqlConnection(System.Configuration.ConfigurationManager.AppSettings.Item("strConn"))

   saveLogfile(MasterID, IID, Usernaam, "In saveData serverside (solldetail_wijzigen.aspx) geraakt op: " + Date.Now().ToString())

   cn = conn
   cmd.Connection = cn
   cmd.CommandType = CommandType.StoredProcedure
   cmd.CommandText = "uspSoll_SollDetailUpdate"
   cmd.Parameters.Add("@MasterID", SqlDbType.Int).Value = MasterID
   cmd.Parameters.Add("@IID", SqlDbType.Int).Value = IID
   cmd.Parameters.Add("@PostID", SqlDbType.Int).Value = PostID
   cmd.Parameters.Add("@FunctieID", SqlDbType.Int).Value = FunctieID
   cmd.Parameters.Add("@StatusID", SqlDbType.Int).Value = StatusID
   If ResultaatID = 1 Then
      cmd.Parameters.Add("@ResultaatID", SqlDbType.Int).Value = 0
   Else
      cmd.Parameters.Add("@ResultaatID", SqlDbType.Int).Value = ResultaatID
   End If
   cn.Open()
   Try
      cmd.ExecuteNonQuery()
   Catch ex As Exception
      saveLogfile(MasterID, IID, Usernaam, ex.Message.ToString)
   End Try
   cn.Close()
End Sub

I have searched for this bug for 2 days, but I could not solve it. Can anybody please let me why sometime works, sometime not.

Thanks in advance. Juliando