If you want to check your PID, try
pid_checksum.py. This is a python script, like mobidedrm, but all it does is check the PID and tell you if it is wrong (i.e. if the 9th and 10th digit, the checksum, indicates a badly formed PID). See a good generic explanation of how to use python scripts, by
Peake.
You may also be able to get your DR1000S PID from your FictionWise Account page. As daffy4u says, this is only useful if you want to strip the DRM in order to read the ebook you bought on your Kindle. This is thought by some to be illegal in the US, but it is hard to see who it hurts.