I am writing a small app that links into Umbraco (a small stand-alone console application that will eventually run as a scheduled task on the server) and I'm using the Umbraco APIs (4.5.2) to make changes to the database/document.

Here is a fragment of what I'm doing:

IEnumerable<Document> documents = Document.GetChildrenForTree(parentDocumentId);
foreach(Document doc in documents.Where(d => d.Published))
{
    doc.getProperty("myData").Value = "some data"; // Exception here
    // ...other stuff here...
}

However I always get a NullReferenceException because there are no properties. This confuses me because I can see that there are 5 properties in the umbraco interface.

A colleague suggested that I use a Node instead of a document, however I can't even create one as I get a NullReferenceException from the Node class constructor.

Node myNode = new Node(-1); // NullReferenceException here

Does anyone have any ideas?