jlm,
Did you not ever have the same sort of take with your previously tried bugs? Did you try the other bugs the same day?
Like Rick says, maybe it was their mood, for whatever reason.
I know we are danged LAZY, so a #10 dark booger is our standard "start" bug....no thinking that way. Interesting how the fish require different presentation styles day to day....sometimes by the hour.
.....lee s.
PS - Being that lazy suits us.....we are always fishing. However, the "sometimes we're catching and sometimes we're watching" outcome needs to be graciously accepted or satisfaction and "feeling of accomplishment" may elude you.