Hello, I have installed relax 3.2.3 on CentOS release 6.6. The program runs fine except for the error: "ImportError: relaxation curve fitting is unavailable, the corresponding C modules have not been compiled." I installed relax using the command: scons install I have searched the archives and see that others have had similar problems, but cannot find a solution that works for me. Any suggestions on how to install or compile the C modules? Below is the output from "relax -info" Thanks, Mark [nmradmin@nmrbox_wisc ~]$ relax --info relax 3.2.3 Molecular dynamics by NMR data analysis Copyright (C) 2001-2006 Edward d'Auvergne Copyright (C) 2006-2014 the relax development team This is free software which you are welcome to modify and redistribute under the conditions of the GNU General Public License (GPL). This program, including all modules, is licensed under the GPL and comes with absolutely no warranty. For details type 'GPL' within the relax prompt. Assistance in using the relax prompt and scripting interface can be accessed by typing 'help' within the prompt. ImportError: relaxation curve fitting is unavailable, the corresponding C modules have not been compiled. Processor fabric: Uni-processor. Hardware information: Machine: x86_64 Processor: x86_64 Processor name: Intel(R) Xeon(R) CPU E5-1620 0 @ 3.60GHz Endianness: little Total RAM size: 3832 Mb Total swap size: 3967 Mb Operating system information: System: Linux Release: 2.6.32-504.1.3.el6.x86_64 Version: #1 SMP Tue Nov 11 17:57:25 UTC 2014 GNU/Linux version: CentOS 6.6 Final Distribution: centos 6.6 Final Full platform string: Linux-2.6.32-504.1.3.el6.x86_64-x86_64-with-centos-6.6-Final Python information: Architecture: 64bit ELF Python version: 2.6.6 Python branch: tags/r266 Python build: r266:84292, Jan 22 2014 09:42:36 Python compiler: GCC 4.4.7 20120313 (Red Hat 4.4.7-4) Libc version: glibc 2.2.5 Python implementation: CPython Python revision: 84292 Python executable: /usr/bin/python Python flags: sys.flags(debug=0, py3k_warning=0, division_warning=0, division_new=0, inspect=0, interactive=0, optimize=0, dont_write_bytecode=0, no_user_site=0, no_site=0, ignore_environment=0, tabcheck=0, verbose=0, unicode=0, bytes_warning=0, hash_randomization=0) Python float info: sys.floatinfo(max=1.7976931348623157e+308, max_exp=1024, max_10_exp=308, min=2.2250738585072014e-308, min_exp=-1021, min_10_exp=-307, dig=15, mant_dig=53, epsilon=2.2204460492503131e-16, radix=2, rounds=1) Python module path: ['/usr/local/relax', '/usr/lib/python2.6/site-packages/requests-2.4.3-py2.6.egg', '/usr/lib/python2.6/site-packages/pip-1.5.6-py2.6.egg', '/usr/lib/python2.6/site-packages/distribute-0.7.3-py2.6.egg', '/usr/lib/python2.6/site-packages/setuptools-7.0-py2.6.egg', '/home/nmradmin', '/usr/local/ccpnmr/ccpnmr2.4/python', '/usr/lib64/python26.zip', '/usr/lib64/python2.6', '/usr/lib64/python2.6/plat-linux2', '/usr/lib64/python2.6/lib-tk', '/usr/lib64/python2.6/lib-old', '/usr/lib64/python2.6/lib-dynload', '/usr/lib64/python2.6/site-packages', '/usr/lib64/python2.6/site-packages/PIL', '/usr/lib64/python2.6/site-packages/gst-0.10', '/usr/lib64/python2.6/site-packages/gtk-2.0', '/usr/lib64/python2.6/site-packages/webkit-1.0', '/usr/lib64/python2.6/site-packages/wx-2.8-gtk2-unicode', '/usr/lib/python2.6/site-packages', '/usr/lib64/python2.6/site-packages/Scientific/linux2'] Python packages and modules (most are optional): Name Installed Version Path minfx True 1.0.7 /usr/local/relax/minfx bmrblib True 1.0.3 /usr/local/relax/bmrblib numpy True 1.9.1 /usr/lib64/python2.6/site-packages/numpy scipy True 0.7.2 /usr/lib64/python2.6/site-packages/scipy wxPython True 2.8.12.0 (gtk2-unicode) /usr/lib64/python2.6/site-packages/wx-2.8-gtk2-unicode/wx matplotlib True 0.99.1.1 /usr/lib64/python2.6/site-packages/matplotlib mpi4py False epydoc True 3.0.1 /usr/lib/python2.6/site-packages/epydoc optparse True 1.5.3 /usr/lib64/python2.6/optparse.pyc readline True /usr/lib64/python2.6/lib-dynload/readline.so profile True /usr/lib64/python2.6/profile.pyc bz2 True /usr/lib64/python2.6/lib-dynload/bz2.so gzip True /usr/lib64/python2.6/gzip.pyc io True /usr/lib64/python2.6/io.pyc xml True 0.8.4 (internal) /usr/lib64/python2.6/xml/__init__.pyc xml.dom.minidom True /usr/lib64/python2.6/xml/dom/minidom.pyc relax information: Version: 3.2.3 Processor fabric: Uni-processor. relax C modules: Module Compiled File type Path target_functions.relax_fit False