Lightmap problem

Hello !

i have a noob problem, i gat a static mesh i create in 3ds max and when i import it in UE and i build light, that’s what happend :

I know that problem has been resolve multiple times on the forum, but i just dont get it…
It’s a lightmap problem i think, that’s what i read.

I hope you will help me because it drive me crazy haha
And sorry for my English, i’m French :wink:

Go through every step of this Lightmap tutorial