That's hilarious. Where's the like button?!
It did strike me that 210gm of dex was a shit-ton of priming sugar for something to end up flat. If you have 23 litres of beer fermented at 19C, 210gm dex should give you a carbonation of around 3.2 vols. Waaay above what you'd normally prime a pale ale style to, and high even for something like a hefe. Try a calculator such as this:
http://webspace.webring.com/people/ms/s ... lator.html next time you prime. Don't get too bogged down in what "Beer temp" means, there's lots of argument, which seems to end up agreeing (sort of) that it's the highest temperature your beer reached for any significant period during fermentation. i.e. if you're fermenting your beer at around 18, but it creeps up to 19 occassionally, just use 19.
That calculator will tell you that 23 litres of beer, fermented at 19C and carbonated to a 'normal' level of say 2.8 vols, would need only 177 grams of dex. Remember to use the volume of what you expect to go into your priming bucket...for example if you are fermenting 23 litres of beer, but you usually leave 1.5 litres behind for the trub, you only need to enter 21.5 litres in the calculator.