Right now I have a datagrid (dgvResults) that shows results of all the records in the table CS_Comm. When I make a change to a select record in an editable cell and click the 'Save' button, I get the error 'System.InvalidOperationException' {"The ConnectionString property has not been initialized."} and points to _sdaAdapter.Update(_dt).

Any idea why this is happening?

Code:
    Dim _sdaAdapter As SqlDataAdapter
    Dim _dt As DataTable

    Private Sub Commissions_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        Me.Icon = My.Resources.AppIcon
        LoadData()
    End Sub

    Sub LoadData()
        dgvResults.DataSource = Nothing
        dgvResults.Rows.Clear()

        Try
            Dim connection As New SqlConnection
            Dim sqlCommand As New SqlCommand
            connection.ConnectionString = GetConnectionString()
            connection.Open()

            sqlCommand.CommandText = "SELECT * FROM CS_Comm ORDER BY CS_Comm_ID desc"
            sqlCommand.Connection = connection

            sqlCommand.Parameters.Clear()

            _sdaAdapter = New SqlDataAdapter(sqlCommand)
            _dt = New DataTable
            _sdaAdapter.Fill(_dt)

            Dim sqlCB As New SqlCommandBuilder(_sdaAdapter)

            connection.Close()
            connection.Dispose()

            dgvResults.DataSource = _dt
            dgvResults.Columns(0).ReadOnly = True
            dgvResults.Columns(1).ReadOnly = True
            dgvResults.Columns(10).ReadOnly = True
            dgvResults.Columns(11).ReadOnly = True
            dgvResults.Columns(12).ReadOnly = True
            dgvResults.Columns(13).ReadOnly = True

            tslWarning.Text = "Records: " & dgvResults.RowCount - 1
        Catch ex As Exception
            tslWarning.Text = "ERROR: " & ex.ToString
        End Try
    End Sub

    Private Sub btnSave_Click(sender As System.Object, e As System.EventArgs) Handles btnSave.Click
        _sdaAdapter.Update(_dt)
    End Sub