The DM-425 modules have been produced in both a PCIe Gen1 and PCIe Gen2 version. Both are compatible with any PXI Express chassis but the Gen2 modules support the higher speed transfers (5 Gbps) of PCIe Gen2.
The type of module in your system is easily identifiable by looking at the front panel of the module. The Gen2 version of the module includes a "Fault" LED that is not present on the Gen1 module. If downloading a new driver please make sure you are downloading the correct driver for your module type.