knockout.js viewmodel null property values after ajax post to controller action method

My Issue:  I am unable to post my knockout.js model to my MVC controller action.  When the action method is executed I have an instantiated model, however all the properties for the model are null.
My Question:  What am i doing wrong?  Why are my knockout model property values null when received into my controller action method?
 
 
Here is my knockout model
function caseItem(data) { var self = this; data = data || {}; // Persisted properties self.CaseNumber = ko.observable(data.CaseNumber); self.CustomerName = ko.observable(data.CustomerName); self.ModelNumber = ko.observable(data.ModelNumber); self.SerialNumber = ko.observable(data.SerialNumber); self.TechName = ko.observable(data.TechName); self.EvalDate = ko.observable(data.EvalDate); self.ReturnReason = ko.observable(data.ReturnR ...