@Carl Love 

Thank you for your quick reply Dr. Carl Love. I tried your suggestion but it did not change anything. I am still not getting the mesh grid on the 3d graphs. What happened is that I ran some examples on fractals from this website: http://ftp.informatik.rwth-aachen.de/maple/frame03.htm

After that I was not getting the mesh grid on the 3d graphs. Any idea from you or another person is very welcome. Thank you all in advance.