Updating af GridView - maybe a viewstate issue - asp.net

Question

I am trying to update GridView with a lot of records through an ObjectDataSource. I am only updating the changed records, so I use ViewState to check if the original datatable has changed. It works fine on my localhost/IIS but when I try the same solution on the deployment server it gives me an error:
Index was outside the bounds of the array.
In this line of code:
Dim row As System.Data.DataRow = originalDataTable.Select(String.Format("ID = '{0}'", currentID))(0)
Below is an example of my code. Is there a problem with ViewState on the server?
Private ProdNum As String
Private tableCopied As Boolean = False
Private originalDataTable As System.Data.DataTable
Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound
If e.Row.RowType = DataControlRowType.DataRow Then
If Not tableCopied Then
originalDataTable = CType(e.Row.DataItem, System.Data.DataRowView).Row.Table.Copy()
ViewState("originalValuesDataTable") = originalDataTable
tableCopied = True
End If
End If
End Sub
Protected Sub btnUpdate_Click(sender As Object, e As EventArgs) Handles btnUpdate.Click, btnUpdate1.Click
originalDataTable = CType(ViewState("originalValuesDataTable"), System.Data.DataTable)
For Each r As GridViewRow In GridView1.Rows
If IsRowModified(r) Then GridView1.UpdateRow(r.RowIndex, False)
Next
' Rebind the Grid to repopulate the original values table.
tableCopied = False
GridView1.DataBind()
End Sub
Protected Function IsRowModified(ByVal r As GridViewRow) As Boolean
Dim currentID As Guid
Dim currentNyhed as Boolean
currentID = Guid.Parse(GridView1.DataKeys(r.RowIndex).Value.ToString())
currentNyhed = CType(r.FindControl("CheckBoxNews"), CheckBox).Checked
Dim row As System.Data.DataRow = originalDataTable.Select(String.Format("ID = '{0}'", currentID))(0)
If Not currentNyhed.Equals(row("News").ToString()) Then Return True
Return False
End Function
The GridView is bound to an ObjectDataSource with these basic settings:
<asp:ObjectDataSource ID="ObjectDataSource1" ViewStateMode="Enabled" EnableViewState="true" runat="server" InsertMethod="Insert" OldValuesParameterFormatString="original_{0}" SelectMethod="GetDataByOverruled" TypeName="DSoverskrivslisteTableAdapters.Shop_Products_Egenskaber_OverrulingTableAdapter" UpdateMethod="Update">
The whole thing is based on this tutorial below. Instead of SqlDataSource I am using the ObjectDataSource which - as mentioned - works fine when run on my localhost, but gives me the error when uploaded to the deployment server.
http://msdn.microsoft.com/en-us/library/aa992036(v=vs.90).aspx
Please help.