*Sigh*
That's because the SB goes only so far back when not logged in. If you kept scrolling up, you'd find it, but it could be a massive chore.
So, do this. Go to the 1 million thread, because that seems to be the depository for all SB entries. Do a search of yourself and enter in the date. You prolly need to go the advanced search route.
Not too complicated, but still time consuming enough.