Not had need to do any solder ring fittings for a few years now. Recently have done a couple of lots last today where I, like previous attempt, could not get a ring of solder to appear. My technique is the same. The joints do not leak but I do like to see the solder ring as it gives me confidence in its integrity. Both sets of fittings are the same batch couyld they ebe faulty or has there been any change? though I doubt that. Oh by the way am using same gas torch as in previous years.