Now, when you say you had a hard time regulating heat, does that mean you think you were too hot or not hot enough? Keep in mind that you want to focus your heat primarily on the lug until you're nearing a good temperature indication from the flux (the flux I use bubbles, then "glows", then goes almost clear when it's at temp), then bring the tube up to temperature. If the lug is hot and the tube is cool (relatively), it won't work, and vice versa. Also, you're focusing your flame on where you want the silver to go, and work systematically and methodically.