if you get no error message, how do you know it fails? it might just as well have reached a conditional statement and based on that don't run.
or, you didn't set your classpath right, and your OS doesn't know what to do with your .jar file.
In general a jar will run on any higher jre version. It's possible you may run foul of tighter security settings, as there have been a number of changes there since 1.5.
How exectly does it "fail"? - absolutely nothing happens - runs but wrong results etc?
Did you try running the jar with java.exe (as opposed to the normal javaw.exe) so you can see the console output?