First, I usually give my bottles about 3 weeks to fully carbonate. Especially when using sugar based materials such as honey, molasses, maple sugar, etc, it is important to allow the yeast to adapt to the new sugars and consume them.
Next, leave the bottle in the fridge for a few days. It takes a while for the CO2 in the bottle to absorb into the beer. You didn't say if you got any small 'pop' when you opened the bottle or not. When I have tried to rush a bottle, I usually get a good 'pop' as the pressure is relieved but very little actual carbonation of the beer.
Are you using pop top bottles or are they twist off? I stick to pop top bottles as I have had mixed results with capping twist off tops without some leakage. It takes a good technique to consistently get a sealed closure on them. You can also check for leaks on any type of bottle by inverting it and looking for beer seeping out. Poor capping may be allowing the gasses to escape instead of being help to be reabsorbed into the beer.
If it comes to adding more sugar to the bottles, try table sugar and use a small measuring spoon to add it to each bottle. Make sure the bottle is well shaken when recapped.