I have two bushes. One blooms and the other next to it has never bloomed. Are there some bushes that never bloom or is there a problem I don't see.
If you have the common bottle brush, Callistemon citrinus, it is hermaphrodite (male and female flower parts), so any plant of this species should bloom. The answer is most likely an issue with growing conditions or management. Do you perhaps shear the plant and cut off all the flower buds in the process? Have you built soil fertility with compost, mineral amendments and mulch? Do you fertilize or water the non-blooming plant differently than the other? Is there pavement, lawn area that gets daily watering excess, or other compromise in growing conditions?
You haven't provided a photo or much information, but this article has some general information on some factors to consider. And an Internet search showed me several other articles on the subject: