Boiled Icing/Royal Icing

I'm beginning my annual cookie bake off for the holidays and I make sugar cookies to decorate with Royal Icing. This year I wanted to do a bit more intricate work and decided that I would make "fluffy Boiled Icing" from the recipe that was included with my Meringue Powder. It said that this recipe was perfect for writing and stringwork. Which is what I was going for. So it's megingue powder mixed with cold water. Then you make a syrup with granulated sugar, corn syrup and water. Bring to to a boil for about 5 minutes and then add it to the first mixture and beat until stiff and glossy. Well it got glossy but never stiff. It's more like a flooding recipe than anything else. Now this recipe didn't call for any powdered sugar and I have seen other recipies that call for powdered sugar..could this be a mistake in the receipe? Can I add powdered sugar to what I have to make it stiffer? Any help would be appreciated.

Thanks, I sort suspected as much. Made another batch and it turned out perfect. So lesson learned.