Custom Key Flexfield error

Hello All - This is my first visit to this forum and am looking for some technical guidance on a particluar issue we are facing in our customization.

we are running out of Attribute columns in MTL_SYSTEM_ITEMS_B that we could use in a DFF. But the Business needs more information to be captured by the Application. so we thought of creating a custom KFF and called it from a seeded DFF. we actually saw this solution from a website :  http://www.oraclebusinessapps.com/?p=71

so we created a Custom Table and a Sequence in our custom Schema, Registered the Table; created a custom KFF on this Custom Table; created a DB "Before Insert" trigger on the custom Table that would create a record with the custom seq.nextval going into the custom Table column Code_Combination_Id; created a Value Set of type SPECIAL whose validation routines of Edit, Load, Validate invokes the custom KFF; plugged in this value set to a new segment that we added to the seeded Inventory DFF : Items.