This trope occurs when a character attempts to accomplish a spell or mystical feat that another character has previously successfully accomplished by merely copying or repeating their words/actions and failing for the titular reason.
In YuYu Hakusho, a demon named Rando, who steals techniques by observing them once attempted to use a shrinking spell on Yusuke, but he failed since Yusuke had his ears full of algae and the spell only works if the victim hears it, which Rando wouldn't know having stolen most his techniques.
In The DCU, Johnny Quick's sidekick Tubby Watts tried reciting Johnny's magical formula of ("3X2(9YZ)4A") [[hottip:*:It is a nonsense formula, do not bother searching for it.]] in order to give himself superspeed like Johnny's. It failed. A later Retcon established that the 'formula' was actually a personal mantra that would only work for Johnny (and eventually his daughter).
Present in The Dresden Files. Wizards intentionally use nonsense words for magic, because words with real meaning make it hard to control.
The time in Harry Potter when Harry tried to use the Cruciatus Curse on Bellatrix Lestrange would definitely work though; it was really weak because he didn't actually want to hurt her all that much and any Unforgiveable Curse requires a desire to hurt the target.
Another Harry Potter example, it is made quite clear that a wand and an incantation do not magic make, you have to be a wizard to use magic. Filch trying to learn magic via Quickspell would be an good example.
The fact that wizards have to go to Wizarding School. You can't just say the words and wave the wand, you have to know how to do it.
And for yet another Harry Potter example, though it's an aversion, Parseltongue (the ability to speak with snakes) apparently is not magical as such. Ron is able to open the Chamber of Secrets by just making the same sounds that Harry did when he opened it.
Charmed only a magical being, such as an actual, magical, witch, can cast spells. If a mortal tries it, the mortal is just speaking a rhyme.
A Subversion in the episode Animal Pragmatism, episode 13 season 2, a group of [[Muggles mortals]] (mortal= non magical "normal" human) cast a spell by playing a tape recording of Phoebe chanting a spell, and it worked, because Phoebe did the rhyming.
A variation appears in an episode of Xena where several people attempt to cast a magic spell from a scroll, to no effect. Gabrielle deduces that they are using the wrong meter and accidentally casts the spell herself. Hilarity Ensues.
In most games that have verbal spell components, either required or voluntary (e.g. Dungeons & Dragons and Shadowrun, respectively), a mundane person speaking the words will have no effect at all: you have to have magical power/knowledge for the spell to work.
Cargo cults, pacific island tribes whose islands were used as bases by various militaries in WWII. From the islanders' point of view, these military people didn't have to farm their own food - instead they built an airbase and called for food and other supplies to be brought down in cargo planes. After the soldiers left, the islanders tried to call for supplies themselves and built their own airbases; but since they were only copying appearance and didn't understand the underlying technology, the planes never came...
Five hats means that five tropers think it is ready to publish.
You are saying that you think this draft is ready to be published. That means the description is not ambiguous,
it doesn't duplicate an existing trope, there are at least three examples, and the title makes sense.
Is that what you meant to do?
You are saying this draft has a ready-to-publish hat it does not deserve and you are taking it back.