Not sure if I've given you the right advice now. From that pic it looks like you're using a pressure release valve. Doesn't that mean you will have to add CO2 afterwards?
More info here:
http://www.thebrewshop.com/contents/en-uk/d79.html
That keg is fine for what you are using it for. I do the same with mine. It sounds like the right amount of sugar. How long have you had your beer in there?
Keep in mind it works the same as a bottle. It will need at least three weeks before the gas spreads into the beer (if that makes sense)...