datagrid, manual render column not work

hi,

I have in MainWindow()  this code:

dgUsers.DataContext = persons;

In xaml have this code and works super:

<DataGrid Name="dgUsers" ItemsSource="{Binding}"  CanUserAddRows="True"> </DataGrid>

But i need manual render columnt and this code dont work:

<DataGrid Name="dgUsers" ItemsSource="{Binding}"  CanUserAddRows="True" AutoGenerateColumns="False"><DataGridTextColumn Header="Name" Binding="{Binding Path=Name}"></DataGridTextColumn></DataGrid>

Where is mistake? Thanks