[2005] Insert value from textbox into datagridview? Code included

[o9z1]

I have a list box that is populated with data. When an item from the listbox is double clicked, the value is displayed in a textbox on the form. With the click of the "Change" button, I want to push that textbox value to index 4 in my DGV. Here is what I tried with no luck.

This all occurs on the click event of the Change Button

For Each row As DataGridViewRow In Form1.GroupDataList.SelectedRows
     row.Cells(5).Value = txtSearch.Text
Next 

Any ideas why this wouldn't work?

I don't get any errors, but nothing happens either.