Susflex

Hi everyone, I've been banging my head against this for about 48 hours and can't really find a solution online. I feel like I'm on the 5-yard line and I'm likely missing something silly but I can't figure it out. Here we go: Added an item to item_template. Server start logs were throwing errors so I was successful in adding the item to the item.dbc file, server side. Error no longer populating in server logs. Used Ladik's MPQ Editor. Empty .MPQ and created a new folder called "DBFilesClient" and added the new Item.dbc file. Named the .MPQ file "patch-5.MPQ" and placed in the Data directory in the client. Launched WoW.exe and received a critical error. Error #131, File Corrupt. File = DBFilesClient\Item.dbc Do these .MPQ files have to be signed or anything? I cannot find a resource online on how to add custom items. Thanks for any and all help. I appreciate it!