Object reference not set to an instance of an object.
at Infragistics.Windows.Ribbon.QuickAccessToolbarPanel.RemoveVisualChildren() at Infragistics.Windows.Ribbon.QuickAccessToolbarPanel.OnIsItemsHostChanged(Boolean oldIsItemsHost, Boolean newIsItemsHost) at System.Windows.Controls.Panel.OnIsItemsHostChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e) at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e) at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args) at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType) at System.Windows.DependencyObject.InvalidateProperty(DependencyProperty dp) at System.Windows.StyleHelper.InvalidatePropertiesOnTemplateNode(DependencyObject container, FrameworkObject child, Int32 childIndex, FrugalStructList`1& childRecordFromChildIndex, Boolean isDetach, FrameworkElementFactory templateRoot) at System.Windows.StyleHelper.ClearTemplateChain(HybridDictionary[] instanceData, FrameworkElement feContainer, FrameworkContentElement fceContainer, List`1 templateChain, FrameworkTemplate oldFrameworkTemplate) at System.Windows.StyleHelper.ClearGeneratedSubTree(HybridDictionary[] instanceData, FrameworkElement feContainer, FrameworkContentElement fceContainer, FrameworkTemplate oldFrameworkTemplate) at System.Windows.StyleHelper.DoTemplateInvalidations(FrameworkElement feContainer, FrameworkTemplate oldFrameworkTemplate) at System.Windows.Controls.Control.OnTemplateChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e) at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e) at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args) at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType) at System.Windows.DependencyObject.InvalidateProperty(DependencyProperty dp) at System.Windows.StyleHelper.InvalidateContainerDependents(DependencyObject container, FrugalStructList`1& exclusionContainerDependents, FrugalStructList`1& oldContainerDependents, FrugalStructList`1& newContainerDependents) at System.Windows.StyleHelper.DoStyleInvalidations(FrameworkElement fe, FrameworkContentElement fce, Style oldStyle, Style newStyle) at System.Windows.StyleHelper.UpdateStyleCache(FrameworkElement fe, FrameworkContentElement fce, Style oldStyle, Style newStyle, Style& styleCache) at System.Windows.FrameworkElement.OnStyleChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e) at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e) at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args) at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType) at System.Windows.DependencyObject.InvalidateProperty(DependencyProperty dp) at System.Windows.FrameworkElement.UpdateStyleProperty() at System.Windows.TreeWalkHelper.InvalidateOnTreeChange(FrameworkElement fe, FrameworkContentElement fce, DependencyObject parent, Boolean isAddOperation) at System.Windows.FrameworkElement.ChangeLogicalParent(DependencyObject newParent) at System.Windows.FrameworkElement.RemoveLogicalChild(Object child) at Infragistics.Windows.Ribbon.XamRibbon.VerifyParts() at Infragistics.Windows.Ribbon.XamRibbon.OnApplyTemplate() at System.Windows.FrameworkElement.ApplyTemplate() at Microsoft.Expression.Platform.WPF.WpfViewNodeManager.EnsureElementInDictionary(Object root, ViewNode knownAncestor)

My code is:

<igRibbon:XamRibbonWindow x:Class="Ribbon.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300" xmlns:igRibbon="http://infragistics.com/Ribbon">
    
    <igRibbon:RibbonWindowContentHost>
        <igRibbon:RibbonWindowContentHost.Ribbon>
            <igRibbon:XamRibbon Theme="Office2k7Silver">
                <igRibbon:XamRibbon.QuickAccessToolbar>
                    <igRibbon:QuickAccessToolbar>
                        <igRibbon:QatPlaceholderTool  />
                        <igRibbon:QatPlaceholderTool  />
                        <igRibbon:QatPlaceholderTool />
                    </igRibbon:QuickAccessToolbar>
                </igRibbon:XamRibbon.QuickAccessToolbar>
            </igRibbon:XamRibbon>
        </igRibbon:RibbonWindowContentHost.Ribbon>
    </igRibbon:RibbonWindowContentHost>
</igRibbon:XamRibbonWindow>

The problem happens as soon as I put the Theme property in the Ribbon.

As soon as I remove it, the problem is gone.

I've removed the TargetID from the QuickAccessToolbar to reduce the code. This is just a demo project to show the problem.

It seems that the toolbar is throwing the exception at infragistics.Windows.Ribbon.QuickAccessToolbarPanel.RemoveVisualChildren()

I'm using Infragistics NetAdvantage 2010 Vol 1 with the SR or 02-April 2010 

Thank you.