I do not like to use chocolate chips for dipping candies or cookies for just the reason you mentioned. Not sure if you melted over a double boiler or microwave? most microwaves these days are too powerful to slowly melt the chocolate and actually just cook it! You will get a better result if you melt it slowly over simmering water and use a good quality chocolate product. I swear by the ghiradelli candy dipping bar (available in a 2.5 lb size at Sam's club)--glossy look, shelf stable. I have posted a picture of my maple cream buckeyes using their product, http://www.food52.com/recipes...

As lorigoldsby explains, you'll be much better off if you use a true dipping chocolate for, well, dipping. The quantity and quality of its fats are very different and suited for dipping, then setting up at room temperature.

I've found that if you can't find dipping chocolate, a little vegetable shortening works better than oil because it's solid at room temperature.

All chocolate has a different tempering temperature. If you don't melt it to the right temp it won't harden. For fancier chocolates you can google the temp or it will be on the packaging.