Easy solution, make sure whatever you just added has a model to it. If you just added fashion/apparel then you need to make sure you have a model that is hex edited to recognize your item, also make sure you compiled(of course) iteminfo.
Removing items in iteminfo is as simple as just deleting that line. Just because the numbers don't go in the correct order, like 1, 2, 5, 7, etc. it will still work. Just don't have any 2 items with the same id. If you don't have any hex editors I highly suggest you get one as it will be needed when adding new items for a character to equip.
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That is one of many hex editors you can use. All you do is open the item's model that you modified with it and find that item's texture name, change it to the new image of your edited item's image in the texture folder.
Ok for example, 0000740002 <-- lance bd armor look. You will find that number next to the BD sets for armor and it corresponds to lance's texture look. You can look in the texture folder of your client and find this as file 0000740002.bmp, you will take the number on and go to the model's folder search and come with a lgo file that you copy somewhere else then open with the hex editor. At this point you want to search for 0000740002.bmp, you will now need to change it to whatever number, for example 9000740002.bmp and save the lgo as 9000740002.lgo and go to the 0000740002.bmp file in your texture folder and change the file name of that to 9000740002.bmp and save it.
Find your item and attach 9000740002 to the lance portion for armor. Now you are ready to compile your new iteminfo, restart server and add to your client. This explaintation may have been horrible, but hope it helps lol