AJAX webmethod declaration in VS 2015

I have recently upgraded to VS 2015, and I now have trouble with declaring AJAX webmethods using VB, specifically the underscore.

I have this declaration:

Public Class AJAX
    Inherits System.Web.UI.Page<System.Web.Services.WebMethod()>
    Public Shared Sub opdaterVideoStat(ByVal playlist_id As Integer)
        TV2BGlobal.opdaterVideoStatistik(playlist_id)
    End Sub
End Class

As I understand it there MUST be an underscore after the webMethod()> for this to Work, but visual studio 2015 automatically removes it every time I try to insert it.

And I cannot get the AJAX functionality to work.

I have another application which has been ported from VS 2012 to VS 2015, and in that app the underscore stays, and the AJAX functionality works.

Whats up with this?