VersionNotFoundException: There is no Proposed data to access

[=?Utf-8?B?VEhhZ2d5?=]

Hello,

a running application was transfered to another server an now brings above
error message. .NET Framwork Version 2.0.50727.42, ASP.NET Version
2.0.50727.210

Backround: I create a dataset with information from a database request. I
create a Session, add the dataset and one row of data. Then I have the
statement "row.BeginEdit()".

If eg. a textbox is changed I write the changes:

Dim row As DataRow = _
CType(Session("DS"), DataSet).Tables(0).Rows(0)
row("Name") = txtName.Text

At the end, I want to show the user, which data was changed with original
and changed data by the following coding:

Dim row1 As DataRow = CType(Session("DS"), DataSet).Tables(0).Rows(0)
Dim row2 As DataRow = CType(Session("DS"), DataSet).Tables(0).Rows(0)

Dim tblUI As New Table
Dim tblUIrow As TableRow
Dim tblUITcell As TableCell
Dim tblUIcell As TableCell
Dim item As Integer
Dim numItems As Integer = row1.ItemArray.Length
Dim title As String() = {"GID", "EMail", "Surname", "First name",
"Telephone", _
"Department", "Location", "Country",
"Company", _
"Boss", "Superuser", "SAP-login",
"SAP-printer"}

tblUIrow = New TableRow
tblUIrow.Style.Add("Font", "bold")
tblUIcell = New TableCell
tblUIcell.Text = " "
tblUIrow.Cells.Add(tblUIcell)
tblUIcell = New TableCell
tblUIcell.Text = "old:"
tblUIrow.Cells.Add(tblUIcell)
tblUIcell = New TableCell
tblUIcell.Text = "new:"
tblUIrow.Cells.Add(tblUIcell)
tblUI.Rows.Add(tblUIrow)

For item = 0 To numItems - 1
If Not row1(item, DataRowVersion.Current).ToString() = _
row2(item, DataRowVersion.Proposed).ToString() Then
......

I assume, that with some kind of server settings the proposed data now is
empty if no changes occured. Unfortunately I can not debug on the new server
and in my VMWare I have no problems.

Does anyone have an idea? I'd really appreciate it, as the app hasn't been
working for a week now and users are getting uneasy :-/
If a German developer can help, you can write in German. I'm posting in
English for the larger amount of readers (or so I hope).
--
Regards
THaggy