Dunno if it's simple. What app are you trying to run?
AFAIK /tmp needs the sticky bit: chmod 1777 /tmp
If that ain't doin it, and you're damn sure you got all the required configs, supplied the right flags, files and whatnot, (and double checked it all) then I'd run a strace on it: "strace -v -o <logfile> <dosomething flags, etc etc>", then peruse <logfile> for errors. If unsure, post here.