Note that I am flying blind here as you haven't provided any sensible, meaningful and detailed information about your setup.
If you gave some sensible, complete and detailed information, someone may be able to help you, such as your platform (Mac or Win), exact versions of your OS, of Photoshop CS4 (11.what?) and of Bridge, machine specs, what troubleshooting steps you have taken so far, etc.
There are no clairvoyants or mind readers here.
Please read this FAQ for advice on how to ask your questions correctly for quicker and better answers:
Each camera model’s raw (i.e. Nikon NEF, not NEC) files must be supported specifically, and Adobe only adds new camera support to currently shipping products, so if your camera model is newer than when CS4/ACR5.7 were the currently shipping versions, then your choices are to pay for an upgrade to the currently shipping version of CS or CC, or use the current version of the DNG Converter (which is 8.4 at the moment) to convert your NEF files to DNGs which would be operable in older versions of the CR plug-in as long as you have set the DNG compatibility options to something less than or equal to whatever version of ACR you’re trying to use.
The DNGC 8.4 can be found on Adobe’s updates page: