Define awful. And check other threads of this type.
One definate problem is that you used bakers yeast. That's said to leave a yeasty taste since the strain is for bread where you want a yeasty taste. Use a brewing yeast. I believe Yoop recommends a champagne yeast for it's clean taste.
Or use a co2 tank and force carbonate things.
Was it sweet enough. Does mccormick have the right flavor for a drink? (test this by using plain soda water from the store if you have to)