None of my Extension Methods are showing in Code behind

Question

I have a number of extension methods defined in my current project. It is a VB.NET project. I have no problem using these methods inside files that are in the App_Code directory, this is the same place that I defined the methods. However, in my page.aspx.vb code behind page these methods are not showing up. I have tried including the correct namespace, with no luck.

Does anyone have an idea as to why I can't call an extension method in a code behind file?

Defined in the App_Code folder

<Extension()> _
Public Function GetSelected(ByVal apps As List(Of Appointment)) As Appointment
    Dim selected = From a In apps _
                   Where a.Selected = True

    Return selected.Single
End Function

Defined in the App_Code folder, inside another class(this one works just fine)

Public ReadOnly Property Selected() As Appointment
    Get
        Return _appointments.GetSelected()
    End Get
End Property

Defined in the App Root folder, inside a code behind file(Not working)

Public ReadOnly Property Selected() As Appointment
    Get
        Return _appointments.GetSelected()
    End Get
End Property

They are all in the same application, no external references. And When I build the project there are no errors, until I try to use the extension method in the code behind. At that point the error is 'GetSelected' is not a member of 'System.Collections.Generic.List(Of Appointment)'

Answer 1

Make sure your module is marked Public.

Answer 2

Try to call the methods "normally" - i.e. as if they were standard shared methods. If you can do so without fully qualifying the type with the namespace, something very odd is going on. Can you use any other VB9 features?

If you can only call it by fully qualifying the type, then it's an Imports issue.

If you can't call it at all, it's a reference issue - but I'm afraid I've had problems with App_Code myself before now in ASP.NET, and basically don't have enough ASP.NET mojo to help any further. Hopefully answering these questions should help someone who is competent to help you more though :)

EDIT: Okay, so you can't use any VB9 features (try something other than LINQ to be certain) and you can't access a shared method from the App_Code directory. Do you have colleagues with Visual Studio? Can you try it on their machines? It sounds like something's very wrong with your installation.