One UNSPSC mapping works and another fails with the same internal category.

For punchout setup, when creating mappings between UNSPSC and internal categories, some mappings fail with error message as 'invalid category', however, other UNSPSC maps to the same internal category without any error. How can I fix this? Example shown below.

Row inserted successfully	46171509	8.1.2 Office Furniture
Insert failed	49121601	8.1.2 Office Furniture