Problems with DataAdapter.Update

I'm getting an odd error when trying to update a database through a DataAdapter.

Here is a simplified version of the problem in code:

VB Code:

Private Sub frmTemp_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Dim cn As OleDb.OleDbConnection
    Dim da As OleDb.OleDbDataAdapter
    Dim cb As OleDb.OleDbCommandBuilder
    Dim ds As New DataSet()
    Dim dr As DataRow
    Dim sSql As String
 
    cn = New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;" & _ 
    "Data Source=" & Application.StartupPath() & "\dbAppraiser.mdb")
 
    sSql = "SELECT * From tblParticipants " & _ 
    "ORDER BY iParticipantID"
    da = New OleDb.OleDbDataAdapter(sSql, cn)
    cb = New OleDb.OleDbCommandBuilder(da)
 
    da.Fill(ds, "tblParticipants")
 
    ds.Tables("tblParticipants").Rows(2).Item("sFirstName") = "Tom"
    ds.Tables("tblParticipants").Rows(2).Delete()
 
    da.Update(ds, "tblParticipants")
End Sub

Now, the database connection works fine. I can read the rows from the DataSet without any problem in another section of the application.

If I comment out the line that deletes a row it works without a hitch. The database is updated, everything is happy.

However, if the delete statement is used I have been getting the following error:

"An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in system.data.dll"

This error does not occur on the ...Delete() line but when the DataAdapter is updated. When I checked the DataSet the row is deleted and acts properly in all ways that I coudl tell.

The worst part is that it used to work (all of this code is of course spread through the application) but I had trouble deleting the row the user was looking at (something I assumed to do with the way I had assigned the row to a new DataRow object). However, even now that I have distilled it down to the bare minimum it still fails.

Any ideas?

Tom