You editted the code for top99neo.m which you should not have done. You need to restore the code to the original -- in particular you need to restore the first line of code to be
function top99neo(nelx,nely,volfrac,penal,rmin,ft,ftBC,eta,beta,move,maxit)
After that, at the MATLAB command line give the command
top99neo(120, 40, 0.5, 3, 1.5, 1, 1, 0.5, 2, 0.2, 500)