I replaced some length of copper pipe and some elbows on the hot water side or the return outlet of the hot water tank as there were a couple of tiny leaks. I soldered everything nicely except in one section after using the cutter, I may have made a tiny cut since it turns out that there is still a tiny leak. So after sanding that part a bit, added some flux, that section of copper pipe is not getting hot enough for me to apply the solder.
There is nothing that I did differently. As a note I am using a propane tank. I again turned off the cold water leading to the tank, opened up the hot water tap in the upstairs kitchen and drained most of the water from the tank. I am assuming that there is still water in the system, which is why maybe the pipe is not getting hot enough. But I drained most of the water. I was able to solder that same section the first time and this is with everything practically assembled as part of the main system. I hope I described the situation accurately.
Any help would be appreciated.