JSON Array of Objects to Model in WebAPI using FromBody

I am creating a Web Api method that should accept a list of objects via XML or JSON and add them to a database.

Here is a very basic version of what I currently have:

[HttpPost]
public HttpResponseMessage Put([FromBody]ProductAdd productAdd)
{
    //do stuff with productadd object
    return Request.CreateResponse(HttpStatusCode.OK);
}

The model structure of the list of objects it accepts is as follows:

public class ProductAdd
{
    public List<ProductInformation> Products { get; set; }
}

public class ProductInformation
{
    public string ProductName { get; set; }
}

The above works perfectly when I am using XML - (Content-Type: application/xml)

<?xml version="1.0" encoding="utf-8"?>
<ProductAdd>
    <Products>  
        <ProductInformation>
            <ProductName>Seahorse Necklace</ProductName>
        </ProductInformation>
    </Products>
    <Products>  
        <ProductInformation>
            <ProductName>Ping Pong Necklace</ProductName>
        </ProductInformation>
    </Products>
</ProductAdd>

But when I attempt to feed the same thing in using JSON (Content-Type: application/json), the Products list is empty

{
  "ProductAdd": {
    "Products": [
      {
        "ProductInformation": { "ProductName": "Seahorse Necklace" }
      },
      {
        "ProductInformation": { "ProductName": "Ping Pong Necklace" }
      }
    ]
  }
}

Is there an issue with the JSON serializer when there is an array of objects within another object ?

Any ideas on what will fix this ?

Thanks

Edit: What serializers are you using for XML and Json? XML: XmlSerializer JSON: Newtonsoft