两个控件这间的数据绑定

<dxe:ComboBoxEdit  Name="dxeQuantityUnit" 
                     DisplayMember="ComboItemName"  ValueMember="ComboItemCode"
                     Style="{DynamicResource ResourceKey=CENullStyle}"
                     SelectedItem="{Binding ElementName=cbeDoseUnit, Path=SelectedItem}"
                     SelectedIndexChanged="dxeQuantityUnit_SelectedIndexChanged"/>