Hi there my friend,

Welcome to DV. First of all, Congrats on your LD . Now regarding about your semi-lucid experience(the one where the RC didn't work), it's natural for an RC to not work in certain dreams. One thing I suggest to you is don't just depend on one RC, it would help if you know a large variety of RCs. Try reading this Reality Check Tutorial to know more RCs. Secondly, it's natural for first-timers to have an LD that lasts only in seconds, I suggest you read this Dream Stabilization Tutorial so that your LDs can last longer and you can make out the most of it. Be sure to practice, practice and practice. You'll get used to it in no time. Hope this helps