Can you please load the most recent build (even if on another machine) and prove that you have the same issue? There have been a phenomenal number of changes since then and will require a lot of investigation. Also, did you create an SF Web Project? This is important as if you didn't then the web.config will not be properly initialized.

I'm experiencing the same thing. SF 1.6.6 version when trying to select the business object on a textbox in web forms.

Please, I can´t continue working without this solved because I'm stucked here .

I tried to modify the example and it's the same. When I go to the properties of a textbox and I try to change the BO i'm having the message The ApplicationBasePage could not be located.  Please rebuild project.
I've rebuilded it several times with no diference.

I'm experiencing with web forms trying to emulate the example but I'm geting errors. When I try to bind a TextBox I get this message:

Exception
  The ApplicationBasePage could not be located.  Please rebuild project.

Source     : MicroFour StrataFrame Extensibility

Stack Trace:
   at MicroFour.StrataFrame.Extensibility.BusinessObjectNameTypeEditor.EditValue(ITypeDescriptorContext context, IServiceProvider provider, Object value)

But I have the the ApplicationBasePage and I did rebuilded the proyect. I also have another business object library with the BO in it and I referenced it.

I'm sending you the solution in case is usefull in any way.