How do I acquire shapeless.Generic[T] instances properly - scala

Question

I'm getting my feet wet in generic programming with Shapeless and I'm running into usual beginner problems.
I actually wrote a piece of code that applies a polymorphic function to case classes that compiles and works correctly under Scala IDE but fails to compile under sbt. While trying to minimize the issue I came all the way down the basic example in https://github.com/milessabin/shapeless/blob/master/core/src/main/scala/shapeless/generic.scala and my problems with creating Generic instances still persisted.
I'd really appreciate an explanation why this compiles:
object Example {
sealed class Animal
case class Cat(name: String) extends Animal
case class Dog(name: String) extends Animal
val generic = shapeless.Generic[Animal]
}
while this:
sealed class Animal
case class Cat(name: String) extends Animal
case class Dog(name: String) extends Animal
object Example {
val generic = shapeless.Generic[Animal]
}
and this:
sealed class Animal
case class Cat(name: String) extends Animal
case class Dog(name: String) extends Animal
object Animal {
val generic = shapeless.Generic[Animal]
}
fails to compile with:
could not find implicit value for parameter gen: shapeless.Generic[example.Example.Animal]
not enough arguments for method apply: (implicit gen: shapeless.Generic[example.Example.Animal])shapeless.Generic.Aux[example.Example.Animal,gen.Repr] in object Generic. Unspecified value parameter gen.
I'm using shapeless 2.3.0 with Scala 2.11.8.
Thanks is advance!