How can i add icon for webmenuitem in menuselected handle?

in webbutton pressed handle I create new webmenuItem and then inside menuselected handle i want to check enables items and then add icon or remove icon from items like this code:

Select Case Item.Value
Case "Descrizione"
  if item.Enabled= false then
    item.Enabled= True
    item.Icon = WebPicture.BootstrapIcon("check2",color.Red)
    item.Enabled= false
    item.Icon = Nil
  end if
End Select

but does not work BootstrapIcon!!