Toby, how long did you wait?
i too, thought that my triops were a no-show. as per my established process of doing things, i hesitated a few weeks before tossing the water out.
lo and behold, three weeks (or was it four? this was years ago) after giving up, a lumpy monster became visible, skimming under the scum liquid, as prescribed in the directions...
i say, don't give up the boat just yet