How do I bind my oxyplot graph to a specific property in my model?

I've started working with Oxyplot for my mobile application. Whilst I can get it working with static values that I define I'm struggling to get it to work with my model.

My model grabs data from my Azure database, the model looks like this.

    using System;

    namespace MyProject
    {
        public class tbl_utilisation
        {

            public string id { get; set; }
            public string psv { get; set; }
            public string ahts { get; set; }    
        }
    }

I'd like to return `ahts` to my line graph as one series and `psv` to my line graph as another series. I thought perhaps something like

    <oxy:PlotView Model="{Binding tbl_utilisation}">
        <oxy:Plot>
            <oxy:Plot.Series>
                <oxy:LineSeries ItemsSource="{Binding ahts}" />
                <oxy:LineSeries ItemsSource="{Binding psv}" />
            </oxy:Plot.Series>
        </oxy:Plot>
    </oxy:PlotView>

This however throws an exception of:

`System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.`

Can anyone help me understand where I've gone wrong and perhaps assist me in getting this graph working? The documentation on the site is'nt the best at the moment so I am finding my way in the dark just now.

Many thanks