What type of tarp ridge line do you use with the Figure 9's?

I currently use the Backpacking Light AirCore Pro "UrsaLite" Dyneema Bear Bag Hanging Cord. It's 2.2mm and slightly slick. It seems to not hold in the Figure 9 (small size) very well. When I pull on one side to tighten the other comes loose.

Thanks for any help!

Bill