jrafael, don't use syntax "sh PlaneShift_CBV0.3.018.bin", you are starting binary file, not shell script.
If "./PlaneShift_CBV0.3.018.bin" gives You that "Syntax error" message, You downloaded file is probably corrupt. Run:
md5sum PlaneShift_CBV0.3.018.bin
and compare obtained string with the one showed in already mentioned thread:
Installing on Linux and important information.. If it is different, You must redownload PlaneShift (maybe from different mirror).
EDIT: --> FYI: sh = ./
FYI: You are wrong...