Calling a web api 2.0 webservice call from xamarin.forms

Hello, thanks for any help in advance. I'm getting an unhandled exception error while calling my call. It is hosted via my local iis at this time. I can make the call in the browser and this returns all the json i need. However, this just isn't working for me. Attached is the code and error I'm getting in the device log.

` public async void GetSampleOrders()
{
try
{
HttpResponseMessage response = await client.GetAsync("api/samples?userid=3869");
if (response.IsSuccessStatusCode)
{
var formatters = new OurObservableCollection() { new JsonMediaTypeFormatter() };

                var list = await response.Content.ReadAsAsync<OurObservableCollection<FSP2_Sample_GetSampleOrders>>();
                SampleList = list;
            }
            else
            {
                SampleList = new OurObservableCollection<FSP2_Sample_GetSampleOrders>();
            }
        }
        catch (Exception e)
        {
            string error = e.Message;
            throw;
        }
    }`

thanks so much for your help! This is a real tough bug to crack.