Autocomplete doesn't always work in Radcombobox

Question

I've noticed that the first time I click in a radcombobox, the autocomplete doesn't work. It doesn't matter if there is previous data in the combobox or the combobox is blank, the autocomplete does not work.

To get it to work, I have to either select something first, or reselect the previous entry.

Is there a way around this? Thanks

XAML:

                        <telerik:RadComboBox x:Name="cboUpperDoorStyle" 
                                         FontSize="16" Margin="0,8,0,0" Background="#F6F8FA" BorderBrush="#D7D8DD" 
                                         ItemsSource="{Binding}" Text="{Binding upperDoorStyle, Mode=TwoWay}" 
                                         TextSearch.TextPath="DoorStyle" IsEditable="True" Style="{DynamicResource RadComboBoxStyle3}" >
                        <telerik:RadComboBox.ItemTemplate>
                            <DataTemplate>
                                <Grid>
                                    <Grid.ColumnDefinitions>
                                        <ColumnDefinition Width="50"/>
                                        <ColumnDefinition Width="200"/>
                                        <ColumnDefinition/>
                                    </Grid.ColumnDefinitions>
                                    <TextBlock Grid.Column="0" Text="{Binding DoorStyle}"/>
                                    <TextBlock Grid.Column="1" Text="{Binding Description}"/>
                                    <TextBlock Grid.Column="2" Text="{Binding Price}"/>
                                </Grid>
                            </DataTemplate>
                        </telerik:RadComboBox.ItemTemplate>
                    </telerik:RadComboBox>

Binding:

        Dim da As New SqlCeDataAdapter(s, myConn.xxx)
        Dim dt As New DataTable
        da.Fill(dt)
        thisCombo.ItemsSource = dt.DefaultView

        thisCombo.IsTextSearchEnabled = True
        thisCombo.StaysOpenOnEdit = True