Lan and Laa Are Not the Same

Rule of Emphatic Negation in Future with "Lan" (لَنْ)

The previous level used لَا for negation without changing the displayed Mudhaari' form.
This level uses لَنْ, which is different in two ways:

Effect on formMeaningParticle
no governing changepresent/future negationلَا
governs the Mudhaari' formemphatic future negationلَنْ

So do not treat لَنْ as simply another spelling of لَا.