Is your client reading the itemInfo.lub? If it is, make sure the the following parts are correctly filled with you sprite info:
If your client is reading the following txt files:
idnum2itemdesctable
idnum2itemdisplaynametable
idnum2itemresnametable
num2itemdesctable
num2itemdisplaynametable
num2itemresnametable
Make sure all the information of your custom sprite is correctly in them. May be there is a spelling mistake, that's my guess.