Quit using the microwave. The bud has to simmer in the butter on low heat for at least 30 minutes to get all the THC out of it.
If you're a grower you can also throw in the leaves, simmer it, and filter through a cheese cloth. The butter will be greenish.
You can also just get a pan, heat it up, throw the bud on it and cook it. But this takes practice, it took me a couple months to do this without burning the bud. This is my preffered way of doing it, since the THC is already activated, you can put it into anything you want. After I cook mine I like to put it in ice cream.