Problems with x10sll-hf memory slot

[Regis Manzke]

Hi, I have a motherboard model X10SLL-HF I'm using an i5-4400 processor, I'm having the following problem, only the P1-DIMMA1 and P1-DIMMA2 slots are working, slots P1-DIMMB1 and P1-DIMMB2 does not recognize anything. Would you help me?
sorry for my English