How old are both of your dragons? If they are are very young you shouldn't worry. I have 2 young dragons that both used to love to eye me whenever I was in the room. They would be interested by the crickets but then when they were about the get them they would look up at me and the cricket would get away. After about a month of getting used to their enclosure and to me, they stopped doing this.
Are they being housed in the same tank? If they are, this is why one of them is thriving and the other isn't. If housed together you should separate them as soon as possible.
Also could you list what you have in your enclosure, as well as temperatures and your lighting/UVB sources, as these could be factors attributing to your problem.