I'd guess that your illness is a very valid reason. Maybe they give you a hard time for not letting them know but if you were really sick then I'm sure they will accept it.
Thank you so much. I indeed called them before the test for my illness, but the call agent told me I don't have to do anything and can just wait for the next test time or hearing, so I refrained from taking further actions. As during years around 2012, I guess CIC still uses the old procedures for no-shows on test and hearings.
