Looking at the dates, I suspect Game 10025924
has been sitting quietly in your inbox for the last 10 days. You've moved, your opponent hasn't. Perhaps he's waiting to finish the other game first - or he hasn't noticed it sitting quietly in his inbox!
If you delete that game (no cost to either of you in terms of win/loss or rating because it's fewer than 3 moves) you'll free up that sixth spot.