Perhaps, but one thing I would do is to take them out of the plastic box. Seeds actually need oxygen exchange to occur for germination to be successful and having your jiffies in a plastic box would be limiting their supply of oxygen. Seeds also do not need hyper humid conditions to germinate, in fact hyper humidity is, no doubt, the leading cause of seeds rotting before they sprout. Remember too, seeds need moist conditions and not wet/soggy conditions which again reduces oxygen exchange. Having your jiffies under a gentle light while waiting for them to sprout can be a good idea, as a little warmth from above will encourage germination a little, plus your seedlings will have access to light in the event that you are not around to switch the light on once they have broken through the surface of the jiffy. Good luck and don't give up just yet!
Only cuttings/clones need extra humidity to survive, due to the fact they do not have a root system to provide water for them for the first few days, while waiting for new roots to grow.
Hope this helps,..... Organoman.