In Orchard CMS I have a service that pulls data from an external data source, and loads the data into an Orchard Content Part. The Part has a migration that welds it with a title part, and I have a route so that my controller is being hit via a URL:

I am using a controller to access the item via a URL, much like the Blog Part controller. However I can't render my part...
The Blog Controller does similar to the following:

```
    var asset = _assetService.Get(1234);
    if (asset == null) return HttpNotFound();

    var model = _services.ContentManager.BuildDisplay(asset); 

    return new ShapeResult(this, model);

```

But if I do this, the 'BuildDisplay' method looks for asset.ContentItem but this is null, despite deriving my part from 'ContentPart'.

What do I need to do to get my data to display?