[Pharo-users] "Instance of SampleForm did not understand #myInstanceVariable"

I am going through the "Spec UI framework" manual and creating a simple UI interface for a program I am writing. When I do a: foo := SampleForm new openWithSpec. I am getting the following error: "Instance of SampleForm did not understand #okButton" okButton is an "instance variable" of the [SampleForm] class and for some reason the class method is not seeing it. The exact line that brings up this error is here: SampleForm class >> defaultSpec ^ SpecLayout composed newRow: [ :row | row add: #okButton ] <----- error happens here origin: 0 @ 0 corner: 1 @ 0.7; yourself Am I missing something incredibly simple? Should I refer to a instance variable with a hash tag in front of it?