It seems that the ISI foton files have been moved to the userapps directory, and the old location is now a softlink to the new location. e.g.
/opt/rtcds/lho/h1/chans/H1ISIITMY.txt is a softlink to 
/opt/rtcds/userapps/release/isi/h1/filterfiles/H1ISIITMY.txt

(see https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=4093 for more info about this change, real documentation will be forthcoming.)

To support this file move, I have updated the SEI tool get_filenames.m so that it will follow a softlink for the foton file location. It will not work on a windows machine, and will only follow the link one step, but it should work, once the {SeismicSVN}/Seismic/Common/MatlabTools/ directory is svn up ed.

See the SEI log for some more info: https://alog.ligo-la.caltech.edu/SEI/index.php?callRep=126