Minimum Purchase Error

Product:Quantity:Price:Total:FE-MTU-12V2000, size - 12″ Diameter x 15 1/2″ Tall Strait1$15.00$15.00FE-MTU 12V4000- 12V 4000 M60R, size - 16″ Diameter x 13 1/2" Tall Strait1$16.00$16.00FE-184- GM Detroit 8V92 Single Turbo 6062TK20 60 series 375hp, size - 9″ Base Diameter x 14″ Tall cone1$15.50$15.50FE-196- GM Detroit 12V71 Natural and dual Turbo-2Brthr, Size - 9″ Base Diameter x 9″ Tall Cone shaped1$15.00$15.00FE-C6CTA- Cummins Series C 6CTA Size, 8 1/2" Diameter x 11" Tall cylinder shaped1$13.50$13.50 (5) Error  Error => Minimum Purchase quantity of 6 units required for this group. (Rule ID = 541)