Originally Posted by Mustardman
I'll second this. I've never had the problem you're describing, and I've tied LOTS of girth hitches in sewn loop webbing to carabiners, anchors, and lots of other stuff over the years. But if for whatever reason it's not working for you, the water knot is the way to go.
I'm a little confused. A water knot is for tying two pieces of webbing together, not, as I understand, for making a loop using just one free end. In fact, with that slippery webbing I've been using, I cannot find any knot that makes a loop that holds. For example, a figure 8 loop falls apart instantly. All I can think of is what Grizz said in message 64, above, which is to make a loop and then grab the two ends and use it a single cord to attach it to the webbing with a double sheet bend.