I gave up on this about 2 years ago, but it seems multiple people have had this problem also. Even if you bought the official adapter it won’t work anymore after iOS 8 is installed. Granted iOS 10 is almost out now, but its not like its going to get fixed. I finally looked back into this issue, seems like the many reviews for it and the digital AV communicate the same thing. Which sucks because these adapters cost $30 but now we have to buy new ones just because they changed something and now they old official ones don’t work anymore.
According to one of the comments:
You need to BUY a updated 1.0 VGA Adapter – it MUST say its a 1.0 or its the older unit. Be careful because a ton of the old adapters are still in stock at Apple stores, retailers, Amazon and eBay.
So fork out another $30 for an adapter you already had, or I guess if you have the receipt you might be able to take it to the Apple store to let them know it failed.