"Microsoft.Crm.Sdk.Data.Services.Entity reference is not valid" error while trying to set the RergardingObjectId.

Error 400 :Bad request.Error Processing request Stream.The Property id for specific type Microsoft.Crm.Sdk.Data.Services.Entity reference is not valid. Pls help me to resolve it.

MY code is:

function createREST()

{
    var createEmail= {};
createEmail.Subject= "My Email";
createEmail.atos_customername="Santhosh Deepak";
createEmail.Description="This is my new test Email";
createEmail.RegardingObjectId= {id: "DE3C3D58-93DE-E411-A903-00505684005D" , logicalName: "incident", type: "EntityReference"};
/*
    SDK.REST.createRecord(
         createEmail, 
         "Email",
         function (createEmail) {
         },
         function errorHandler(error)
         {
             alert(error.message);
         }
       );
}