The most confusing Night Vision Mod problem is the one where everything looks right: you press N, the message says ON, and the cave stays dark. The mod's README names the cause directly. This guide explains it in plain terms.
What the README says
Under known conflicts, the README states that the mod will not function properly with shaders such as BSL, because they bypass the lightmap code the mod deals with. BSL is named as an example, not as the only pack affected.
Why that happens
Vanilla Minecraft decides how bright each block looks using a lightmap: a small table that turns block light and sky light into on-screen brightness. When you have the Night Vision effect, the game brightens that lightmap. Night Vision Mod works by telling the game you have the effect, so the vanilla lightmap does the brightening.
Many shader packs replace the way the world is lit with their own lighting code. If a pack calculates brightness without using the vanilla lightmap, then the brightened lightmap is simply never consulted. The mod is still on, as the status message shows, but its effect has nowhere to land.
What you can do
- Turn the shader pack off while you need night vision. In your shader loader's settings, switch shaders off, look around, then switch them back on.
- Check your shader pack's own options. Some packs include their own brightness, night vision or minimum light settings. That is a feature of the pack, not of this mod.
- Use a different pack for building sessions if you rely on night vision often.
Night Vision Mod has no settings of its own, so there is no option inside the mod that changes how it interacts with shaders.
Rule out other causes first
If you are not running shaders and still see no change, the issue is something else. Go through the full troubleshooting checklist, starting with whether the ON message appears at all.