Okay, a few things I am seeing that could cause a problem. How high protein is your dog food? I mix my roach cow as follows 50%cat food(higher protein than dog food), 30% dog food, 10% tropical fish flakes, and 10% honey nut cheerios. They seem to like the sweetness of the cheerios. Here is the important part though, I mix it up in the blender until it is a large grain POWDER, similar to the size of salt or sugar grains. Then I sprinkle all over the enclosure, even on the egg flats. I have a waxworm tub in there that have had the edges roughed up with sandpaper full of water crystals. THEY NEED THE CRYSTALS. It boosts humidity and keeps them from drowning when they drink. I find that even if you take out veg and fruit in the morning you can get a decent amount of fruit flies. So I only offer a quarter of an orange every three to four days and take it out after about 12-24 hours have passed. They usually eat most of it in this time frame. Is your enclosure see through or semi see through? My first rubbermaid was allllllmost see through, but enough light was getting through to REALLY bother them, so I switched to a black tub, and they have started eating and breeding like crazy. Do you have a heat source? The enclosure should ideally be between 85-90*F. Mine is between 80 and 90, depending on where in the enclosure the temp is read from. How are your egg flats set up? If they are not straight up and down(so the poo falls to the ground) It can stress the females into dropping their egg sacks. It also can make the culture smell a bit.
Hope this helps. Feel free to ask any other questions you may have.