Thanks for taking the time to write. Without being able to see your rhododendron, I can't say why it isn't blooming. Some common reasons include:
The plant being shaded too much
The plant being pruned at the wrong time of year
The plant not being hardy enough for your area (so the flowers freeze out every winter)
The plant being too young (if you've only had it a year or two)
The buds being eaten off by deer or other critters
Does one of these sound right? If not, I'd need more information to help give you a more definitive answer.
---Justin, Senior Garden Editor, BHG.com