I had one and had to give it up after trying everything and would not settle to captivity after I tried everything. I don't think age has much of factor and I just generally don't think they made good captives after my experience with them, as I've never the problems I had after keeping loads of amphibians. Might be a hit or a miss though, as I've heard some say they make good pets. I'd suggest getting another toad to give it some company, might make it more bold. Although I haven't had a successful experience, after from caring for loads of amphibians and extensive research on this toads care I can advise some stuff that may be of help.

A 3 sided background is a must for these, as they are skittish. You can get black or green aquarium backgrounds, if you don't like the rainforest ones. If you're using live plants then keep them in the pots for ease of maintenance and so the toad doesn't wreck them. Supply a 2% fluorescent tube covering 2/3 of the length of the tank for the plants and the toad. Try looking online for somewhere that sells plants specificity for reptiles and amphibians, so they're clean of chemicals that could be dangerous and they will be able to recommend some suitable plants.

A heat mat on the wall is pointless. I've tried it many times hoping for good results but unless you have an tree frog that climbs up the wall, they're little use as they only heat the glass and slightly raise the temp an inch or so away from it at best, though work well underneath. A heat lamp or ceramic heat emitter is a better option and as long as you keep the humidity in the tank high and provide retreats, the toad won't dehydrate but you'll probably need to use a fogger and or partially cover the screen top with glass, foil or plastic wrap to maintain humidity.

Here's a good read on their care http://blogs.thatpetplace.com/thatre...s-pets-part-1/

Also I'd recommend the book Frogs and toads by Devin Edmonds, as it has a small section on how to set them up and care for them