wpf Datagrid :Position Listview when Datagridcell textchange

wpf Datagrid :Position Listview when Datagridcell textchange

I want to position a Listview when the Datagridcell text change .My
datagrid has a column namely Product, when the user type something on that
column a small listview popup with Products hence the user can select one
product from the listview and the product is displayed on the datagrid's
Product column .My problem is that I can't position the Listview near the
cell which I edit.
My XAML is :
<!--My datagrid-->
<my:DataGrid Name="dgvSales" BeginningEdit="dgvSales_BeginningEdit"
VirtualizingStackPanel.IsVirtualizing="False" AutoGenerateColumns="False"
Margin="13,150,9,117" KeyDown="dgvSales_KeyDown"
MouseDown="dgvSales_MouseDown"
PreparingCellForEdit="dgvSales_PreparingCellForEdit" >
<my:DataGrid.Columns>
<my:DataGridTextColumn x:Name="naam" Header="Code"
Width="120" Binding="{Binding
ProductCode}"></my:DataGridTextColumn>
<my:DataGridTextColumn Header="Product Name"
Width="200" Binding="{Binding
ProductName}"></my:DataGridTextColumn>
<my:DataGridComboBoxColumn Header="Unit"
Width="100"></my:DataGridComboBoxColumn>
<my:DataGridTextColumn Header="Purchase Rate"
Width="100" Binding="{Binding
PurchaseRate}"></my:DataGridTextColumn>
<my:DataGridTextColumn Header="Qty" Width="100"
Binding="{Binding Qty}"></my:DataGridTextColumn>
<my:DataGridTextColumn Header="Amount" Width="100"
Binding="{Binding
Amount}"></my:DataGridTextColumn>
</my:DataGrid.Columns>
</my:DataGrid>
<!--My listview-->
<ListView Height="161" ItemsSource="{Binding}" Name="lstvwProductCode"
VerticalAlignment="Bottom" Width="388">
<ListView.View>
<GridView>
<GridViewColumn DisplayMemberBinding="{Binding
Path=Record_Id}" Header="Record ID" Width="0"
/>
<GridViewColumn DisplayMemberBinding="{Binding
Path=Product_Code}" Header="Pcode" Width="110"
/>
<GridViewColumn DisplayMemberBinding="{Binding
Path=Product_Name}" Header="Product"
Width="180" />
</GridView>
</ListView.View>
</ListView>