It was to some extent scientific way to plan the intercourse in the fertile period of the menstrual cycle. Since it has not worked, let us try it more scientifically. First get your semen examined from the laboratory. If it is of a good quality, then second step will be to evaluate your wife for the evidence of ovulation (egg release). The best way now a days is by monitoring ovulation by ultrasonography. If she is ovulating, then continue ovulation monitoring and plan your intercourse at the time of ovulation. Usually the egg is released after the follicle is 18+ mm in size. Still if it odes not give you results after a fair trial, then you might have to go for testing for tubal patency. This can be done by filling radio-opaque dye in the uterus and taking an x-ray. Alternatively, it can be evaluated by laparoscopy. If the eggs are not forming, then you will have to undergo complete hormonal work up. I hope this guides you properly.