CL is not very good for AH trading and only monthlies really trade. Generally, you get the fill with slippage.
ES is much better, but it's still not a certainty that you'll get the fill unless the market moves against your order. Still, ES fills are relatively common AH.
Time of day matters as well. There are dead times where little happens. Shortly after the close and before the open, it's relatively easy to get the fill with ES.
