Steema TeeChart>System.NullReferenceException: Object reference not set to an instance of an object

I am trying to use Steema TeeChart to create a gauge in my Xamarin Forms App.
I have a test program from Steema that works fine, but when I embed the exact same code into my project, I get an error : "System.NullReferenceException: Object reference not set to an instance of an object"
on this line of code:

           var chartView = new Steema.TeeChart.TChart(Context);

I've isolated the problem to the right side of the statement, but can't figure out if the problem is coming from the argument Context or the call to the TChart.
All of my 'using' statements seem to be correct, and the same instruction works flawlessly in the sample code. In fact, the renderer .cs file (where this code is located) is an exact copy of the file included in the sample code.
The only differences I've found are:

packages.config:
Sample Code -
""
Project Code -
""

Android Manifest:
Sample -
<?xml version="1.0" encoding="utf-8"?>




Project -
<?xml version="1.0" encoding="utf-8"?>

Packages.config -
Sample -
<?xml version="1.0" encoding="utf-8"?>




Project -
<?xml version="1.0" encoding="utf-8"?>

I hope I've included enough information, but not too much.
Any suggestions are appreciated.
Thanks