Some help about an error

Hello elitepvpers.
I have an problem with some items appearing in game.
When someone logs in with the item equipped you can't see it
If they re equip it then you can see it.
The error that is popping up in the error.log file is
RedoEquip(): Illegal dwParts

I have looked at the source but i am not able to see it.
Can anyone give me an pointer in the right direction.

With kind regards,

dwParts is in which slot your equipment is used.
--> PARTS_RWEAPON, etc..

Yeah i have figured that one out. But still it seem like an odd error.
Maybe cause its parts_RWEAPON but its in the left hand slot.
Could that cause the illegal dwParts error?