Runtime error: undefined symbol: mxCreateDo​ubleMatrix​_730_proxy

I have a C code that calls mxCreateDoubleMatrix:

#include "mex.h"

...

mxArray *mx = mxCreateDoubleMatrix(n1, n2, mxREAL);

gcc flags include: -I${MATLABROOT}/extern/include -L${MATLABROOT}/bin/glnxa64 -lmx -lmex -lmat -lmwspmatrix -lmwmclmcr

The code compiles. But when I run the code, I get the error message:

symbol lookup error: mycode.so: undefined symbol: mxCreateDoubleMatrix_730_proxy

What am I missing here? Which library contains mxCreateDoubleMatrix?