We're gonna need to know about tank size and tankmates, water-changing schedule and, ideally, your water parameters. How long has the tank been set up? How big are the kribs?
I'm assuming the kribs have at least one or two cave structures to choose from for spawning purposes, right?
Are you ever able to really get a good look at the eggs?
If so, what do they look like---i.e. do they turn white fairly quickly? Do you ever see the male fertilizing them? The female fanning them? Does the pair defend the spawning site?
I suppose it could just be that the male is inept when it comes to spawning---you did say that he had similar bad luck with a prior spawning partner, right?
Anyway, give us a little more info. to work with and we'll see if we can maybe narrow it down a bit better.
BV