I'll go along with Rick's questions about type of enclosures, and temperatures.
Other than that - how long have you had them?
You say you have tried lizards - what kind of lizards, and for which snakes?
- a neonate Whitelipped is probably too small to eat a whole pinkie (personally, I usually just sliced pinkies lengthwise and force fed them for a few meals til they could take a whole one...but that is not an approach I recommend, lol). try appropriate lizards or treefrogs...you might want to use a slightly aggressive tease feed technique with this one (don't forget the tail)
- the sidewinder will probably be more inclined to go for small lizards (western US lizards...desert species). This is one that, for whatever reason, I never kept so I can't tell you specifically what kind. I could look it up...but then, so could you
- baby copperhead should be able to handle the pinkie, but tiny frogs can work too. teasing to provoke a strike can be very helpful - again, don't forget the tail