Hi !
Rapture is installed at the same time as Sonar (as you probably know),
but the serial number is different. and has to be registered individually.
you have a 30 day trial period before being "forced" to register it.
You might want to try to run Sonar as administrator (right click on SONARPDR.EXE --- properties--RUN AS ADMINISTRATOR), then try to register again?
I hope that helps !
Cheers !
V