@divya.suresh, I tried looking at the code, but the code that generates the error is hidden, as well as the error message. That said, the following does not seem right :

• Several authentication requests, in lines 37, 40 and 42.
• Several extraction contexts, in lines 37 and 42.

This code looks like it is for scheduled requests. We have 3 tutorials (and corresponding sample code) that describe this in C#, starting with this one. They might be of help.

In a nutshell, the initial part would look somewhat like this:

static void Main()
{
    //Connect and authenticate to the DSS server:
    Uri dssUri = new Uri("https://hosted.datascopeapi.reuters.com/RestApi/v1/");
    string dssUserName = "YourUserId";
    string dssUserPassword = "YourPassword";
    ExtractionsContext extractionsContext = new ExtractionsContext(dssUri, dssUserName, dssUserPassword);            
    string sessionToken = extractionsContext.SessionToken;
    Console.WriteLine("Returned session token: " + sessionToken);

After that, the other operations will simply refer to the extractions context. Example:

//Create a new (empty) instrument list:
var instrumentList = new InstrumentList { Name = "myInstrumentListName" };
extractionsContext.InstrumentListOperations.Create(instrumentList);

Etc.