Ovulation Test HELP!!!!

Hey ladies, my period track/fertile calendar is saying that my ovulation days have started from the 26th April 2016 and yesterday and today are my most accurate days to fall pregnant, however on the 26/04/2016 I have done an ovulation test and it was negative and done another one today and the outcome was the same, NEGATIVE!!! Am I doing something wrong here?!
Thanks in advance x