mex shared library on Linux, __attribute__ ((visibility ("default"))) problem

There is no problem on windows but on linux i got these

i use gcc 4.7 on ubuntu I successful compile C source file with mex command but when i try to loadlibrary i got this error message

Type '' was not found. Defaulting to type error. Failed to parse type '( visibility (" default "))) int NumberOfSetBits ( int' original input '( visibility ...

I try to compile shrlibsample too but i got warning 'no function exist' message

Sorry my bad english

MyFunc.c

#include <stdio.h>
#include <mex.h> 

#include "MyFunc.h"

__attribute__ ((visibility ("default"))) int NumberOfSetBits(int i)
{
  i = i - ((i >> 1) & 0x55555555);
  i = (i & 0x33333333) + ((i >> 2) & 0x33333333);
  return (((i + (i >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24;
}

void mexFunction( int nlhs, mxArray *plhs[], 
          int nrhs, const mxArray*prhs[] )
{
}

MyFunc.h

__attribute__ ((visibility ("default"))) int NumberOfSetBits(int);