Quote - It has to do with the provision that gives the copyright holder control of the creation of derivative works. Within the concept of derivative work lies the trap.

There is no trap in derivatives (made with or without permission).
Derivation creates a nesting of copyright, the really tricky bit is how you determine if derivation has occured rather than original creation.
The trap is that for some defences against an accusation of copyright violation you have to admit to copying/derivation e.g. fair use, that the use is sufficiently transformitive, or that the copied/changed elements aren't copyrightable, whereas competing claims of original creation will be decided by a number of factors e.g. documention of creation, likelyhood of the similarity in the two creations but only after a determination of what elements are actually protectable by copyright has been made.