did you try to update your OCS Agent (to v. 126.96.36.199 or 188.8.131.52) ?
It could also be the content of REG which is problematic :
Have you tried your REG file by running it on a PC whose the registry modification was not made ?
> Optionally, on your client modify the register manually and extract the key (the empty 2 lines at the end of the REG file are obligatory, etc.)
Note : In my case, the "regedit /s file.reg" LAUNCH option works perfectly !