You most likely did this, and the problem is technical rather than procedural, but to confirm:
Load the old save, switch to the required character, right click and 'Edit Item' then click on the Export button and save the Item_Name.lsb file. Next, exit out of the item window, switch to the Load Saved Game tab to load the new save, right click an open slot in a character's inventory and 'Add Item', then click the Import button, select the lsb file, click Open and the Apply.