have done both but crickets,although good when small(pinheads)for feeding young stuff were pretty much a waste of time for what you got at the end of it.They took ages to get to a decent size and also feeding of them they are pretty quick and hide in your tanks.The locusts were a breeze after a few teething probs as you are having now.Change your egg laying medium to pumice sand from garden center,vemrmiculite does work and some swear by it,does not work for me and I use what works for me! get a smaller egg cup,I use see thru throw away coffee cups in a cut out so The top is at floor level,change once a week and cover with gladwrap so you can see when they hatch.I think your prob with eggs not hatching maybe dessication of the eggs?keep them really warm 34 or so at least,at lower temps they lay less and eggs even though layed can be infertile.The other thing to watchis where you get your grass,even traces of spray can do the same.I have only knowen one sucessful cricket breeder and raiser and I got his locusts going for him and he ditched the crickets,way too slow(depending on how many you want of course.Give the locusts a dish of bran to eat as well as grass.