I have RedPower, and I should get RedPower Stone Wafer (recipe: http://goo.gl/KU3KK) when smelting stone, but I get steel nugget. ID's were checked with ID Resolver.
Railcraft 6.14.0.0, Forge 6.6.0.497, RedPower 2 pre 6

Sounds like a ID conflict (don't believe ID Resolver, it lies).