I have been looking for an answer to this problem. I want to do a basic model in lightwave and then import it into zbrush to add details. It looks fine when imported into zbrush but as soon as i subdivide once, it comes out missing polygons. I have tried many ways to model before importing into zbrush and nothing works. Below is a picture of what I am talking about.
This looks like the edges aren’t welded. As a result, they pull apart when the model is subdivided and smoothed.
Im not sure what to weld. I know I dont have any extra points to weld and pretty sure you cant weld edges in lightwave. So, i am not sure of your answer.
It’s probably in the export settings. Each edge that you’ve got there is made up of two points for every intersection. One point belongs to each surface.
For example, imagine a cube with four polys per side. If the points aren’t welded, you’ll have a model that has 54 points. Most of those points are doubled up along the edges. If the points are welded, you’re left with a model that has 26 points.
If you can’t find a setting to export from LightWave with welded points, there’s a setting in ZBrush that’ll do the job on import. Select the Polymesh3D tool (the one that looks like a star). Then increase the Tool>Import>Weld slider before pressing Import.
Aurick,
You are a star, this has been bugging me for ages, so thanks a million for that. Just spent half a day trying to figure out what went wrong.
I can breathe again now…
Peace
also general notes on exporting from lightwave to other apps>>
over in lightwave modeler load up your model and press m [lowercase m] for merge points…btw you want to be in point select mode not poly or edges…let it do auto and that should be fine.
before exporting as an obj switch to poly mode and press the w key, this will bring up the stats panel where you can see the various poly types listed [1point polys, 2 point, tri, quad and greater than quad] and how many polys of that type are in your object…sometimes when you model you may get some 2 point or 1 point polys…these will stop the export to obj so just be aware of that.
if you need to export to obj and you have some 1 and 2 point polys listed simply click the + next to that type to select them in the polystats window [w key to bring that up] and then hit del to nuke those polys.
lightwave itselft can deal with 1 and 2 point polys but other apps can’t…just so you know.
also lightwave 9.5 currently has some problems with the way it makes obj’s so stick to 9.31 until an update comes out to rectify that [it’s on it’s way]
Thanks for the words of advice here. Yeah, makes sense to check all the geometry before exporting. Always goodto be reminded of that… 
Now, if only I could find that damned Tweak command…