Problem With Exported .dae Model in Second Life/OSgrid

Hi all,

I hope I’m posting to the relevant category here on the forum… I’m having difficulty when exporting a model to .dae format and importing it into Second Life/OSgrid. Looking at it in blender, everything appears as normal:

However, when I export it to .dae format and upload it to the game, large chunks of it are missing. As you can see, the towers no longer appear and a part of the upper wall is missing.

Worse still, if I join the separate objects together into one object in blender before exporting, only the front panel of the gatehouse appears and everything else is missing once uploaded to SL:

Any ideas on how to fix this problem and have the entire model show up when imported? :confused: