Installing an ESATA controller in Dell Power Edge 6800

I am trying to install a new Addonics ADSA3GPX1-2E eSATA controller in Dell Power Edge 6800.
I am unable to see a new device in device manager whin I install the card into any of the 4 PCI-E slots. This system also has 2 dell pert 4 raid controllers installed in two of it?s PCI-x slots. They are running 1 mirror set and 2 raid 5 sets. The OS is installed on the Mirror set. The controller is a PCI-E x1 and the server has 3 PCI-E x4 slots and 1 X8 slot. The server is running server 2003 SP2 32bit.
The eSATA controller has been installen into another test 2003 server and ti seems to work fine there, so the controler appears to be ok.
Does anyone have any Idea as to why it cannot be seen?