codice:
Sub MyDtgItemCommand(sender As Object, e As DataGridCommandEventArgs
)
Select Case E.CommandName
   Case "Pippo"
    'Codice da eseguire de viene premuta l'immagine.....
End Select
End Sub
codice:
........
<ASP:DataGrid
........
OnItemCommand="MyDtgItemCommand"
........
/>
........
<ASP:ImageButton ID="MyBtt" Runat="Server" ImageUrl="Percorso"
CommandName="Pippo"/>
........
Se hai problemi dimmelo.