Try just using silver solder, instead of the gold solder. It melts too high to work well on the sterling but regular silver solder, either easy or medium, will solder the two together just fine.

Rich is right do not use the gold solder. I would suggest tinning the back of the gold with medium silver solder and then laying the tinned side onto the silver and heat from below until you see the solder flow on the edges. Remember the axiom "The heat of the metal melts the solder and not the flame". Make sure you flux well and do not overheat. Best of luck.

Fred Zweig
Metalsmith