WCF method called twice

Question

I have a web service which is returning data to the desktop application. The problem I am having is, when the web service returns small volume of data everything works fine but

Answer 1

I recently had this issue.

It turned out that analyzing the WCF log as written by the System.Diagnostics.XmlWriterTraceListener yielded a problem with the data contract I had set up.

I am returning Dictionary (Side Note: Yes, I know this is really bad!, but I am young and need the money). I forgot to include the [KnownType] attribute on the return value for the DataContract:

    [DataContract]
    [KnownType(typeof(Dictionary))]
    [KnownType(typeof(Dictionary))]
    [KnownType(typeof(Dictionary>))]
    public class MyCoolObject: ICoolObject
    {
[DataMember]
        public Dictionary Results
        {
            get { return _results; }
            set { _results = value; }
        }
    }