There is no error message , file "free-energy-landscape.txt" is my file that I generated by using the commands below
 python xpm2txt.py -f free-energy-landscape.xpm -o free-energy-landscape.txt
it's 3 column text file like this :
1.26574 0.04494 16.30000
1.26861 0.04494 16.30000
1.27147 0.04494 16.30000
1.27434 0.04494 16.30000
1.27721 0.04494 16.30000
1.28007 0.04494 16.30000
1.28294 0.04494 16.30000
1.28580 0.04494 16.30000
1.28867 0.04494 16.30000
I took Mathematica script from http://nmr.chem.uu.nl/~adrien/course/molmod/FEL.nb and make changes in it has indicated .  Just change the directory path and file name that is free-energy-landscape.txt ., but I don't know how it run because when I ran it .  It takes my file as input but doesn't give any output results.  Kindly tell me how I can run this file.
I attached my free-energy-landscape.txt file, kindly do check it.