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BindingExpression path error

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Docking
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Joe
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Joe asked on 25 Jul 2012, 05:07 PM
In my ShellV, I have a CustomRegion:

   <telerik:RadDocking HasDocumentHost="True"
                            Grid.Row="3"
                            x:Name="MainRadDocking"
                            BorderThickness="0"
                            Margin="0"                            
                            Background="Transparent">
            <telerik:RadDocking.DocumentHost>
                <telerik:RadSplitContainer>
                    <telerik:RadPaneGroup  prism:RegionManager.RegionName="MainPaneRegion"
                                           Name="MainDockingPanelGroup"/>
                </telerik:RadSplitContainer>
            </telerik:RadDocking.DocumentHost>
            <telerik:RadSplitContainer InitialPosition="DockedLeft">
                <telerik:RadPaneGroup prism:RegionManager.RegionName="LeftPaneRegion"
                                      Name="LeftDockingPanelGroup"/>
            </telerik:RadSplitContainer>
            <telerik:RadSplitContainer InitialPosition="DockedRight">
                <telerik:RadPaneGroup  prism:RegionManager.RegionName="RightPaneRegion"
                                       Name="RightDockingPanelGroup"/>
            </telerik:RadSplitContainer>
        </telerik:RadDocking>

When I launch my application, I am getting 81 errors, here is a sample:

System.Windows.Data Information: 41 : BindingExpression path error: 'PaneHeaderVisibility' property not found for 'object' because data item is null.  This could happen because the data provider has not produced any data yet. BindingExpression:Path=SelectedPane.PaneHeaderVisibility; DataItem='AutoHideArea' (Name='LeftAutoHide'); target element is 'PaneHeader' (Name=''); target property is 'Visibility' (type 'Visibility')

System.Windows.Data Information: 20 : BindingExpression cannot retrieve value due to missing information. BindingExpression:Path=SelectedPane.PaneHeaderVisibility; DataItem='AutoHideArea' (Name='LeftAutoHide'); target element is 'PaneHeader' (Name=''); target property is 'Visibility' (type 'Visibility')

System.Windows.Data Information: 21 : BindingExpression cannot retrieve value from null data item. This could happen when binding is detached or when binding to a Nullable type that has no value. BindingExpression:Path=SelectedPane.PaneHeaderVisibility; DataItem='AutoHideArea' (Name='LeftAutoHide'); target element is 'PaneHeader' (Name=''); target property is 'Visibility' (type 'Visibility')

System.Windows.Data Information: 10 : Cannot retrieve value using the binding and no valid fallback value exists; using default instead. BindingExpression:Path=SelectedPane.PaneHeaderVisibility; DataItem='AutoHideArea' (Name='LeftAutoHide'); target element is 'PaneHeader' (Name=''); target property is 'Visibility' (type 'Visibility')

System.Windows.Data Information: 41 : BindingExpression path error: 'IsActive' property not found for 'object' because data item is null.  This could happen because the data provider has not produced any data yet. BindingExpression:Path=SelectedPane.IsActive; DataItem='AutoHideArea' (Name='LeftAutoHide'); target element is 'PaneHeader' (Name='HeaderElement'); target property is 'IsHighlighted' (type 'Boolean')

What is causing this problem? Do I need to set the bindings to a fallbackvalue? Do I need to create RadPanes within the RadPaneGroups? If so, can you send me an example?

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Georgi
Telerik team
answered on 30 Jul 2012, 11:52 AM
Hi Joe,

It seems like the Prism is showing the Panes a little bit later and at first there are no Panes (SelectedPane)  and therefore the binding crushes. It seems like there is no straightforward solution and if you need we can try to think of any workaround that will suit you best?

Greetings,
Georgi
the Telerik team

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