Generally, that firmware version is not "real"... You have probably done something wrong when naming/creating the VER.REQ file (some people make a mistake and type "G" for "Q"... like "g" vs "q". Try following these instructions and see if this helps:
FAQ - CHDK WikiAnd, lastly, there are only two known versions of the S5is firmware--you can try one, then the other and see which works.
There are no known issues with using the "wrong" version of CHDK -- other than you will need to pull the batteries out to reboot the camera.
Note, you will need to use the "Bootable" method of loading firmware using the "DISKBOOT.BIN" file. The "Firmware Update" method does not work with the S5IS and you will not find a PS.FIR file ("Dry OS" operating system from Canon).
Hope this helps.
-Bill