Modern Hogwarts --Sisiny

Wandwork - Emmett

"One of the simplest spells you can do with your wand..." Professor Flitwick's squeaky voice echoed in the dark, "is illumination. This spell is of course very useful in dark times. It, obviously, creates light but it can also be used to signal to others far away. Lumos," he said loud and clear. A ball of light shone from the tip of his wand. "Now you try. Hold it steady."

The darkened classroom filled with chants of "lumos" from all the students. 

How do they do that? thought Emmett to himself. He'd never seen this particular trick before. He held up his father's wand and said "lumos" as the rest of the class was. Nothing happened. Around him, several students had their wands alight. The white tip of his own wand felt so far away from his magic. "Lumos," he whispered trying to coax the light into the wand. Still nothing. He was thinking this would be so much easier if it were closer to him when Professor Flitwick wandered over to him. 

"Trouble, my dear boy?" he said quietly.

"Uh, a bit, I suppose."

"Try once more. Let me see."

Emmett gave the command again and the wand stayed unlit. 

"Hmm. Headmistress McGonagall told me about the sorting hat bit you did last week. A simple spell like this shouldn't be giving you any trouble." By now, the rest of the students were playing around with their lit wands. "In any case, Mr. Abrams, do a bit of practice. I'm sure you'll get it in no time. You are very talented. I've seen already in class."

Emmett stared at his own wand in the light of everyone else's illuminations as Flitwick continued the lesson on nox, the delumination spell. Emmett's wand had belonged to his father. He used it on stage all the time. Emmett had been excited to see on his Hogwarts list that he would be using a wand and had asked his dad if he could pretty please use his. It would waste their money to have to buy one when his father had a perfectly usable one Emmett could borrow. His father agreed, saying he'd just get a new one for shows. The wand was black with white tips on either end and made of plastic. 

"Having some performance issues, Emmett?" The voice belonging to a boy Emmett was not very fond of, Damien, came from right next to him. He was the boy from Diagon Alley that slapped his father's coin from his hand.

"Just need practice." Emmett ignored the boy's joke and continued to stare at his wand angrily. Flitwick said this was a simple trick. The problem was that the magic wasn't close enough. The tip of the wand was practically miles away. If he could make something light up, like his fingertip...

The whole room had gone dark by now. Then one solitary glow of light pierced the black. 

"Very good, boy," Flitwick said. "I had faith in you."

Emmett said nothing. Nobody could tell, but he had indeed illuminated his fingertip. He tapped the tip of his wand and the ball of light stuck to it instead. He felt as though all eyes were on him, judging him for doing it so late. "Nox," he told the light. Nothing happened, just as before. The class laughed. Emmett glared at the taunting ball of light. He covered his wand tip with his hand, smothering the light silently.

Emmett spent the rest of class attempting to light the tip of his wand instead of his finger. It shouldn't be this hard. He'd done way more complex tricks in front of huge crowds and those came so easily to him.
Why was a bit of light so hard to make?