PXIe-8383mc in Slot 2 is not identified by PXIe-1078

i have a problem with PXIe-8383mc, that is connected to Slot 2 of PXIe-1078 Chassis. After i cannot establish connection via x8 MXI Cable (the pcie card in the host pc is correctly recognized and listed in Device Manager) i connected PXIe-8135 Embedded Controller via LAN-Cable to my PC (Win7, x86).