Replacing a chainring - what did I do wrong?
Consider that you should use either grease on the threads of your chainring bolts when installing chainring bolts, you want to be able to easily remove these later as chainrings do need to be replaced over time. Get some grease on the faces of the chainring and crank spider where they touch the chainring bolts. Some people are fine with blue loc-tite, but I prefer not to have to force it.  

Don't just tighten them once and assume it's ok.  Go around the ring and tighten every other bolt until you've tightened them all. You can do a star pattern if you prefer, just don't tighten them simply in order around the ring.  Make a couple passes and incrementally increase tightness. You want to ensure they are tightened evenly, so that none of them are loose while others are over-tightened. Use a torque wrench if you're really worried about over-tighening.

Make sure you're using the appropriate length of chainring bolts (which doesn't seem like a problem from the photos).  Some bolts (actually the sleeve/nut) are made longer to go through the crank spider and 2 rings (or bash guard), while others are made shorter to go through the crank spider and a single ring.