Vegetable growing advice

I need some assistance from anyone who has successfully grown sweetcorn. My sweetcorn experiment has had mixed results.  I have had some sweetcorn, but I have also had the following: Exposed cobs with no silks...? Now I know that I grew them in an unconventional way (on the retainer wall) but I have harvested a few - I would just like to know why this happened to some of them? I would also