Discrepancy between PT winnings and actual bankroll

[Salva135]

So, I recently deposited into a new Party Poker account and loaded up Poker Tracker for the first time. I've run in the black over my first few sessions, but I've noticed a discrepancy between the net amount won according to Poker Tracker and the actual increase in my bankroll, with the Poker Tracker figure being slightly higher.

My guess was that the rake was accounting for this difference, although PT keeps some sort of rake statistic. So my question is two parts: what exactly is that rake figure representing, and what accounts for the discrepancy?