The biggest problem I see in your setup is the cage size. It is far too small for even a single adult dragon. Two dragons should be housed in a cage at least 5'x2' in floor dimensions and bigger is always better.
Second, how old are the dragons? If they were adults when you bought them a year ago, their age can easily fall between 2-10 years old. If the dragons are over 5 years old now, they are pretty much past their breeding prime and breeding wouldn't be a good ideal to start at this age, especially if the female was bred during her prime.
Third, are you sure you have a male and female? If both are female, that could be why they are not breeding, for obvious reasons. If both are male (though I don't think likely as sexually mature males would have fought each other to death by now in a cage that size) same reason why they have not bred.
Lastly, though not always necessary, some dragons won't breed unless brumated. Basically they need to go through a cooling period for 2-4 months before ready to breed. This cooling period helps 'ripen' reproductive cells (ie eggs and sperm). Cooling is done by lowering the day and night temps gradually over a space of about 2-4 weeks as well as decreasing daylight lengths. Once you reach night time temps of about 65F and daytime highs of about 75F and day length of 10 hours, leave temps/light at these ranges for 2-4 months. The dragons should sleep nearly constantly during this time though it is normal if they come out and bask for a few hours every once in awhile. Don't offer any food during the cooling time but have fresh water available.
After the 2-4 month period, reverse the process by slowly increasing temperatures and daylight lengths over a 2-4 week period till temps are back to normal. Offer food regularly once temperatures are normal and they are up and active again.
During brumation there should be very little weight loss, maybe 20-80g depending on how long they are down. Some stay down for more than 4 months but typically 1-3 months is normal.
Once they have fully warmed up and had a week or two to eat normally, introduce the male and female on neutral ground or in a large tank together. It is better to just put the male in with the female for short periods of time or till you witness copulation a few times, then separate them again. A couple of matings is more than enough for the female to lay several clutches each season.
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PHLdyPayne