Made the oven successfully and used it the other evening- was not a success but then it was minus one out- a combination of too few coals and unrealistic expectations for the insulation perhaps!
I also found that putting the lid on reduced airflow- would you say its best to get it going with the lid off and then put the lid on to allow heat to build? Like I say I may have also been unrealistic when the amount of coals.
ANSWER - Sorry to hear the first attempt did not go well, but stick with it as it will work.
I guess I was lucky getting the balance of coals and airflow right, but me share my experience. The first oven which was the smaller one, I dropped in a few coals to cover the bottom, poured on BBQ lighter fuel and lit. The key thing to note is I left the lid off the top, and there was just one hole in the bottom for air. This oven caught first time, and I just added a couple more coals later. I wasn't to begin with as there wasn't much of a flame at the start, but when I came back later it was nicely burning.
The second was a lot larger and had three big holes in the bottom outer pot and then I drilled a more in the inner bottom pot. Same procedure, lit the coals left the top off and walked away. This time when I walked away I was feeling a lot more confident as I had lots of big flames. But when I came back 5 minutes later it had blown out. I put this down to the airflow being too strong, so this time when I lit it I put the lid on to slow down the air flow. When I came back later the oven was burning beautifully. This second oven catches quicker and burns better than the first oven.
As I say I have been lucky with my oven getting the setup right first time. You just need to play around a couple of times until you get it right for your build. So play around with how many coals you put in to begin with and the position of the lid on top.
For the record I cover the bottom with coals and then put a few on top of these in the middle over the main hole. I have the lid completely on when heating up and half on when cooking.
Also I would be concerned about the temperature outside, as I regularly fire mine up when it is below 0.
Hope this helps.