Unsatisfied Link problems are to do with native code not being available. Please give details of your installation, operating system, etc. Also are you using a 64‑bit machine?
You may need to reinstall Java®.
Additional: Please also give details of what NitGen is.
The error message means that you are running your program on a 64-bit JVM, but the native library you are trying to use is 32-bit.
The "bitness" of the JVM needs to be the same as the "bitness" of the native library. So, if you have a 32-bit native library, then you must use a 32-bit JVM, or you must find a 64-bit version of the native library.