My BJCP ID is 9876; why can’t I login?

That’s not a BJCP ID; that’s the format of a Certificate Number, which is what you get after you pass the online exam.  You need to take a tasting exam to get a BJCP ID and become a member.
 
You’ll get a BJCP ID when the information from the recent tasting exam gets uploaded to our database.  It sometimes takes awhile since it has to go through a few hands.  You’ll get an email when your ID has been created. You can certainly participate in BJCP events.  For people without IDs, your participation gets entered as a non-BJCP judge and we track by name.  So just be sure to use the same first and last name as on the exam.  When your record does get created, we’ll search for retroactive points and move them to your record.