One of the common problems in lucid dreaming seems to be stress, which results in "dry periods" or periods where there is little or no dream production or recall. There's a simple reason for this:

Dreams are a holographic construction of the mind. In contrast to our normal perception of the world, the dream holograph is created from our memories without any external stimulus . This requires an enormous amount of cerebral computing power. When we are overloaded and stressed out with problems, work, anxieties, worries, the amount of cerebral computing power needed for dreams in general -- and lucid dreaming in particular -- is not sufficient.

Hence, during these stressy periods, dream production is low, dream recall is low, and lucid dreaming may be impossible. The situation is like a computer where you don't have enough RAM to run all your programs. Too much stuff going on to allow the brain's dream production program to run effectively.

THE SOLUTION IS SIMPLE, but not necessarily easy. The basic thing is to minimize the effects of stress by meditating, clearing the mind, listening to relaxing music or environmental sounds, and generally living as quielty and simply as possible in order to clear out the overload from your mind.

In general, it's a good idea to spend some quiet time before going to bed to review the events of the day, resolve any conflicts, and solve any problems, so that when you drift off to sleep, these issues don't enter your mind and you can CONCENTRATE ON THE TASK AT HAND, WHICH IS GENERATING LUCID DREAMS.

Hope this helps...