"raising hell" with the administration and threatening after something as inconsequential as a detention is a great way to get on an organization's bad side. I would go straight to the board during a meeting and be diplomatic but firm, citing first and foremost that the online system is not being used as intended. They've paid for the system and they'll be pissed if it's not turning an ROI and utilized.

"My kid is smart but he's doing poorly, something's wrong!" is a quick way to be shown the door, especially if you go in there with the intent to "raise hell". Every kid is a special cookie these days that doesn't deserve anything lower than an A-. Not saying your kid isn't smart or isn't having a bad class experience, but this isn't the way to approach the problem even if its how its manifesting itself. My mother's been a teacher for decades and she's got some great stories in her experience about parents coming in and giving a big stink about their kid's B or C only to find that they didn't turn in a paper or something. Even if your son has earned a better grade or has legitimate complaints, trust me--complaining parents about their kids' grades are dime a dozen, not a good way to approach the execs.

Sorry if this is a bit critical in nature, but I hope it helps...good luck with the situation

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth