Index <Indexname> is used to enforce the full-text key on table <Tablename> and must be single-column. (Visual Database Tools)
You are adding a column to the index that is used as a key for full-text indexing of this table. Proceeding with the operation will disable full-text indexing for this table. Choose Yes to proceed with the operation and disable full-text indexing. Choose No to cancel the operation.
See Also
Concepts
Error Messages in Visual Database Tools