fatal error. *** cross-section tables are missing from xsdir 10001.70m 10002.70m 10003.70m ... bad trouble in subroutine ixsdir of imcn cannot continue with missing cross-section table(s). is the message I am getting. I have created a link using ln -s /file/path/to/LANL/MCNP_DATA/mycustomxsectiondirectory xsdir to direct MCNP to my custom x-section directory when it is looking for xsdir. The custom directory is identical to the xsdir file created during the mcnp install, aside from the names of the libraries. The custom libraries that are listed in the directory are in the same folder with the rest of the libraries from MCNP. My DATAPATH and PATH variables are set to the correct locations in both my .bashrc and .bash_profile files.(DATAPATH is set to the /LANL/MCNP_DATA folder and path is set to the /MCNP5/bin folder) I tried using the default xsdir file to see if it was an issue with my custom directory, and it gave me the same error. I'm not sure why it is giving me this error. It is MCNP5 ver. 1.60. Thanks for any help!