[DFTB-Plus-User] about tools in compiled executables

[juhasz.g.aa]

Dear all,
I have downloaded the compiled executable tar pack, which contains not only the dftb+ software, but also other tools, too. All I done was extracting these files, but I wonder if I need to set some environmental variables?
Most work progam works without problem, but pl xyz2gen gives an error message about dptool library: 

./xyz2gen
Traceback (most recent call last):
  File "./xyz2gen", line 14, in <module>
    from dptools.gen import Gen
ImportError: No module named dptools.gen

What should I set up so the python modules in lib/dptools can be found?
Thank you for your advice in forward.
Best regards,
Gergely Juhasz