It looks (and I admit it's hard to diagnose from just a picture) like you're moving too slow across the middle of the bead. If you're going to weave (and I prefer to), you need to focus your time on the sides, and whip quickly across the middle. Slow motion from one side to the other builds up the center of the weld, and the heat concentrated there makes the time you spend on the sides add more to the middle while you're waiting for the toes to fill. The tighter you can keep your arc the narrower that hot zone will be. You'll need to find the rhythm that works for you but a rule of thumb to start from is to hold one side as long as it takes you to say, "one, two", then move very quickly to the other side and repeat. Now, if you have a Savannah, GA drawl, or a New York snap to your speech, adjust accordingly...
It also helps (especially in a test) to take any measure permitted to prop your arms comfortably so you have full control. In the field, you will often freehand and even one-hand it, but tests are about taking out all the variables that can screw you up.
More advice will show up, I've no doubt, and other eyes may see something I don't. Be patient; We don't move at a facebook pace here.