DataGird A Row

I'm wanting to add a row to my WPF application.

I'm looping through all files in a folder and if it meets some conditions i'll populate them in my Gird. (Conditions not in code yet)

However I can't seem to even add a row to my DataGrid. Why? What's wrong

vb.net Code:

For Each File In Directory.GetFiles(filepath)
                    myDG.Items.Add(New String() {"11", "22", "33", "44", "55", "66"})
                Next

(it loops though my files okay)

Moved to the WPF forum