TextBoxFor displaying initial value, not the value updated from code [duplicate]

Answer 1

You are not setting Altitude. It will be null so the code will never go into this block and set Lattitude to "LATTITUDE"

    if (DataSiteList.Altitude != null)
    {
        DataSites test = new DataSites();
        test.Latitude = "LATITUDE";

        return View(test);
    }