Hello Luca,

I have no problem on my side, however it would help to know where and what you are trying to set.

Some obvious checks:

1) be sure the account under which you are running your PB app on the 64bit box has rights to write in the registry branch;

2) be sure the datatype corresponds to the datatype specified in the valuetype argument;

3) be sure you're actually running a 64bit app (start the Task manager and verify the image name is just "myapp.exe" without a "*32" suffix)

Side note, if you would run in 32bit mode and try to write to HKLM\Software, the key would end up under the Wow6432Node.

Cheers,

Marco