The type or namespace name 'DataMember' could not be found (are you missing a using directive or an assembly reference?)

The type or namespace name 'DataMember' could not be found (are you missing a using directive or an assembly reference?) 


using System.Runtime.Serialization;

        [DataMember]
        public string FileName { get; set; }

Solution:

Add this reference to your project:

System.Runtime.Serialization (System.Runtime.Serialization.dll)

System.Runtime.Serialization