Lazy loading with EF6 and VB2015

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VB

EF5.0

I use VB2015 and EF6. i have an invoiceline table with orderlines. In the invoiceline is a productID. This productID is connected with a foreign key relation to a product table. When i put the invoiceline as a datagridview on a form and the related productname in a label the name in the label changed when i scroll through the invoiceline . However when i change a productID in the invoiceline the name in the label is not changing. When i do this in EF4 it's working as expected. The productname changes immediatly when i changed the productID.Is there a difference between the two version an if so how can i solve it.
This is the code, i create a new form with only a datagrid and a label:

Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
       Dim _context As New dGVEntities
       Dim f = _context.FactuurRegel.ToList
       dgvFactuur.DataSource = f
   End Sub