序列化文件错误

问题：当序列化XML文件时，出现错误
用以下方法：

XmlSerializer lizer = new XmlSerializer(typeof(MyType));

　　错误如：

The assembly with display name 'mscorlib.XmlSerializers' failed to load in the 'LoadFrom' binding context of the AppDomain with ID 1. The cause of the failure was: System.IO.FileNotFoundException: Could not load file or assembly 'mscorlib.XmlSerializers, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The system cannot find the file specified.

　改变方法以下：

XmlSerializer lizer = XmlSerializer.FromTypes(new[] { typeof(MyType) })[0];

　　则问题解决