.net - error message " 'y' is not declared." in vb.net

Question

I'm having a weird problem. I have some code in Visual Studio 2012 express edition in a WPF app written with VisualBasic.Net.

Private Sub txtColProvGenCompany_TextChanged(sender As Object, e As TextChangedEventArgs) Handles txtColProvGenCompany.TextChanged

    ProvNewEditing()
End Sub

But when I try to run the application it says that it can't build because the y from txtConProvGenCompan***y***.TextChanged. The error message is

y is not declared. it may be inaccessible due to its protection level

and shows only that character underlined in my code.

any ideas?