Well, like how LucidPower said, Writers get writers block, and dreamers get dreaming blanks. And also, I think trying to force it to happen sets you back, just surrender and let it come naturally, don't get so stressed out over having lucid dreams! Just have a peaceful confidence that the ability will come when it's ready, and that because you want it, it will come. Everyone takes a different amount of time, for me it was a week or 2 before I started having lucid moments, for everyone it's different. Also, pay FULL attention while doing RCs, ask yourself randomly whenever something weird happens or whenever you remember, "Am I dreaming?" and when you do, say things like "If the clock changes when I look at it again, I'm dreaming." then look away and look at it again, if it stays the same, say "It did not change. this must not be a dream." But it's best to do multiple reality checks, and fully comprehend why you do them as you do, and that will help them be more effective in the dream world?