SilverLight 3.0 DataGrid LoadingRow Event

Question

Following are my Question regarding the LoadingRow event of the Datagrid

1. When will it fires after the Row is bound to the data or after that. As if you debug the Silverlight application then of first execution if you type following code

   ((System.Windows.Controls.TextBlock)(((System.Windows.Controls.ContentControl)(((DataGridRow)e.Row).Cells[1])).Content)).Text

if will return empty string but if your datagrid has scroll (which is in my case , my datagrid has scroll), if you scroll down then the LoadingRow firs again and this time it will return Text on that cell?? why it is not return text on first time and return on second time when i press the scroll bar ???

1. If I paste above code in the cs file then it will return error

'System.Windows.Controls.DataGridRow' does not contain a definition for 'Cells' and no extension method 'Cells' accepting a first argument of type 'System.Windows.Controls.DataGridRow' could be found (are you missing a using directive or an assembly reference?)

Can any one help me in these question

thanks in advance,