The library (.dll) created using MATLAB cannot be loaded into another MATLAB. A DLL generated by MATLAB Compiler SDK is intended to be used by other applications rather than using it back in MATLAB.
If you would like to share your program with other users who may or may not have MATLAB, you can create an executable using MATLAB Compiler. And, this can be executed in MATLAB using bang operator (!) or System command or from Windows command prompt.