Pallete: Drag and Drop issue

Node from palette is not droping onto diagram.

Here is the code for palette
<go:Palette x:Name=“palette”
Margin=“2”
IsEnabled=“True”
InitialScale=“1”
MaximumSelectionCount=“1”
Opacity=“1”
AllowDragOut=“True”
NodeTemplateDictionary="{StaticResource MyPaletteTemplateDictionary}" >
go:Palette.Layout
<go:GridLayout Alignment=“Position” CellSize=“5 5” />
</go:Palette.Layout>
</go:Palette>

Diagram

<go:Diagram x:Name="diagram" Grid.Column="1"
                AllowDrop="True"
                Model="{Binding CurrentNetwork, Mode=OneWay}"
                HorizontalContentAlignment="Stretch"
                VerticalContentAlignment="Stretch"
                ScrollViewer.HorizontalScrollBarVisibility="Auto"
                ScrollViewer.VerticalScrollBarVisibility="Auto"
                LinkTemplate="{StaticResource LinkTemplate}"
                NodeTemplateDictionary="{StaticResource NodeTemplateDictionary}"
                MaximumSelectionCount="1" >
        <go:Diagram.DraggingTool>
            <Tools:SldDragTool DropOntoEnabled="True" FromPortId="Out" ToPortId="In" />
        </go:Diagram.DraggingTool>
    </go:Diagram>

What I am missing here?

Is your target diagram model Modifiable?