This error occurs when the shared library has dependencies which MATLAB® can not find.
On Windows® systems, to find library dependencies, use the third-party product Dependency Walker. Dependency Walker is a free utility that scans any 32-bit or 64-bit Windows module and builds a hierarchical tree diagram of all dependent modules. For each module found, it lists all the functions exported by that module, and which of those functions are called by other modules. Download the Dependency Walker utility from the website http://www.dependencywalker.com/. See http://www.mathworks.com/matlabcentral/answers/92362-how-do-i-determine-which-libraries-my-mex-file-or-stand-alone-application-requires for information on using the Dependency Walker.