How to populate WPF Datagrid with Linq to SQL

Question

Hi so i'm using linq to sql through table mapping. Which works. But as I'm new to C# as well as WPF I seem to be incapable of finding a way to populate a datagrid with IQueryable. My Query looks like this.

var STL = new STDB.reportDB(Properties.Settings.Default.dataConnString);
DateTime startDate = new DateTime(2015,2,1);

IQueryable<STDB.salesInvLine> lastMonthInvoiced = from salesinv in STL.Sales_Inv_Lines
                                                          where (salesinv.Shipment_Date.Year == startDate.Year
                                                              && salesinv.Shipment_Date.Month == startDate.Month)
                                                          select salesinv;

dataGrid01.ItemsSource = lastMonthInvoiced;

This gives me a NullReferenceException error. Which as i understand it doesn't help very much as far as errors go.

I've also tried switching IQueryable with datagrid01.ItemsSource but no dice. I've bumped into examples that utilise the using().to list(); but i cant seem to tailor those methods to my own tables probably because i don't fully understand them. I am able to access individual rows with

foreach (STDB.salesInvLine salesinv in lastMonthInvoiced)
{
      string code = salesinv.Document_No_;
      DateTime ddate = salesinv.Shipment_Date;                
}

But even still I can't figure out how to get this into a Datagrid. If someone could point me in the right direction please that would be much appreciated. I don't wanna have to give up and go back to VB.