Optiplex PCIe slots

Hi,
I have the following problem with my optiplex xe (refurbished).
- the slots PCIe X16 from pc does not see pci card (RAID CONTROLLER MARVELL VA2400S PCIe X4 )
In the bios (System Board menu) SLOT1 appear empty but in the menu Miscellaneous Devices - PCI slots it is enable
Can someone help me with solving the problem?
=sorry for english - it is not native language=
Thank you