Baby bearded dragon pretty inactive

Question
Hello, thanks for taking the time to read my questions. I just recently purchased a baby bearded dragon about a week ago. He's approximately 4 weeks of age (not 100% positive, most places do not sell babies until 6 weeks old), he (thinking he's a male, hard to tell right now) is currently 5 and 6/10 inches long, and I have noticed a behavior of his that differs from the ones similar to his age in videos I've researched online.

I'll go ahead and start off with my equipment list just to be sure that everything looks good.

-40 Gallon Zilla Critter breeder cage (long)
-Fluker's 150 watt lamp-clamp
-Zoo Med 100 Watt Basking Bulb
-Zilla Slimline UVB tube light 20 inches w/Reptisun 10.0 Desert Bulb
-Stick-on Analog thermometers and hydrometer (these will be replaced very soon, have a zilla digital dual-temp probe /hydrometer on the way)
-Reptile Carpet
-Cage Decor (rock basking spot/cave, shallow food and water dishes, 8 inch reptile tree)

He appears to be very observant, although inactive showing a lack of energy and motivation. He spends nearly all of his time at his basking spot in an 8 inch tall fake tree that I picked up in the reptile section at the pet store. He doesn't move around very much, just sits in his tree. I have to take him out of the tree and set him in a spot where crickets will be close in order for him to eat usually. Sometimes he'll go for one, it'll get away and he won't chase it. I usually aid him in getting crickets, knowing that a large cage can make it difficult for a baby beardie to catch crickets. I'm considering purchasing or crafting a cage divider.

Visibly all of his health signs appear to be normal, bright open eyes, recently started shedding, bright colors, attentiveness to surroundings. On a side-note, I previously noticed he was closing his eyes very often for a while, although not for extended amounts of time, and discovered that the basking light was not the proper distance from the cage (12 inches), and I corrected it. His eyes appear to be fine now.

As far as his diet and temperatures are concerned, he's getting about the maximum sized crickets that he can eat (not larger than the distance between his eyes) daily, however he only eats 10-16 per day. I plan to pick up an order of much smaller crickets to be safe and avoid any kind of impaction risk. He only eats about 5-8 at a time, then stops. I'm also gutloading the crickets with a calcium feeder. Also he's refusing to eat veggies (using mustard greens at the moment), no matter how much I attempt to attract him to them with movement. I feed him twice per day at the moment, I also ensure to properly dust all food with a Calcium and D3 supplement. I also mist him twice per day to ensure his hydration, which he learned to lick off of his face.

His daytime cage temperatures (according to the analog thermometers) are approximately 90-92 degrees Fahrenheit on the warm side, and about 80 on the cooler side of the cage. At night they go from 65-75. He's sitting in between 20% and 30% humidity. I'm seriously thinking that the thermometers readings are incorrect, and will know for sure as soon as the zilla thermometer comes in the mail. I'm debating on picking up a cheaper digital thermometer from walmart today to double-check his temperatures and possibly pick up a ceramic heat emitter for extra heat if they are not suitable for him.

I've done a lot of research online both before and after I bought my dragon, ensuring that i'd be a good owner...although I do worry and want to be absolutely certain that I'm taking care of him correctly, this is my first reptile. :) Please let me know if you have any recommendations or have found any red flags that might be causing this inactivity. Thank you!

Answer
 You certainly got the set-up done well.  He may be intimidated by the size of the tank, so putting a divider is is a good idea.  He only needs calcium supplement on his firat twelve crickets, and only needs it about four times a week.  I suggest you get a small bin and have it be the feeding bin.  This way you can keep rogue crickets from trying to snack on that baby at night.  And you can truly monitor how many crickets he's eating.  I would mist more often to get that humidity up a bit to 30-40% and make sure he gets a calcium rich salad ground to a mush in the mornings.  Babies need their veggies.
  I'm thinking it is a temperature problem, even if those temps are accurate, it's much too cool, but if you add the divider, then it may correct, his basking temps should be 100-105 F.