mi correggo:
questa sintassi funziona
codice:Private Sub RadioButtonA_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles RadioButtonA.Init Dim r As System.Web.UI.WebControls.RadioButton = DirectCast(sender, System.Web.UI.WebControls.RadioButton) r.Attributes.Add("onclick", "r_ab_click();") End Sub