Issue with creating Light Map in 3ds Max

I’m using 3ds max’s unwrap uvw modifier to create my UVs for the texturing and for the Light Map. I have my UVs for texturing in the first channel then switch to channel two to create the Light Map. When I switch to channel two however and try to switch back to channel one, my initial UVS are either not there at all or messed up in some way. I’m not sure what causes this or how to fix it either since it only happens with some of my models. Does anyone know what’s going on?

Don’t switch, you just have to create an other unwrap in map channel 2. The first unwrap (diffuse) must be in map channel 1 and the second unwrap (lightmap) in map channel 2. You did something wrong :wink: