.net命名空间引用错误

Question

错误 2 类型“System.Collections.ObjectModel.ObservableCollection”同时存在于“c:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\System.dll”和“c:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\Silverlight\v5.0\System.Windows.dll”中 C:\Users\Administrator\Desktop\ESRI.ArcGIS.Client\ESRI\ArcGIS\Client\DynamicLayerInfoCollection.cs 4 54 ESRI.ArcGIS.Client