Ok...
As El OchoCinco stated...don't make any judgments from just one trade.
In addition, I'm going to assume you're manually managing your entry, exit, stop/loss, profit targets. Simply, you're not using an automated trading system for pair trading ?
Also, for the past few years, it seems like people have had more success in pairs trading when the instruments in the pair are losing their correlation as in the correlation is declining.
wrbtrader
I just tested the pair trade manually.