SQLDataAdapter.Update errors

[JEP]

I lifted the following code directly from MSDN examples. However, the update command fails against my Northwind/SQL Server database.

The code is:
Private Sub cmdStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdStart.Click

Dim catDA As SqlDataAdapter = New SqlDataAdapter("SELECT CategoryID, CategoryName FROM Categories", nwindConn)

catDA.UpdateCommand = New SqlCommand("UPDATE Categories SET CategoryName = @CategoryName " & _
"WHERE CategoryID = @CategoryID", nwindConn)

catDA.UpdateCommand.Parameters.Add("@CategoryName" , SqlDbType.NVarChar, 15, "CategoryName")

Dim workParm As SqlParameter = catDA.UpdateCommand.Parameters.Add("@CategoryID", SqlDbType.Int)
workParm.SourceColumn = "CategoryID"
workParm.SourceVersion = DataRowVersion.Original

Dim catDS As DataSet = New DataSet
catDA.Fill(catDS, "Categories")

Dim cRow As DataRow = catDS.Tables("Categories").Rows(0)
cRow("CategoryName") = "New Category"

catDA.Update(catDS)
The returned error is:

Update unable to find TableMapping['Table'] or DataTable 'Table'.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: Update unable to find TableMapping['Table'] or DataTable 'Table'.

Source Error:
Line 62: cRow("CategoryName") = "New Category"
Line 63:
Line 64: catDA.Update(catDS)
Line 65:
Line 66: DataGrid1.DataSource = catDS
What is Table Mapping? What is going on here?

Thanks in advance