Hi skyjay,
Could be that a couple of vertexes are not merged. Or, you've got an extra face somewhere.
You could also try doing a cleanup.
Sometimes trying to bevel each edge individually will pinpoint were the problem is. Once you figured out the problem and corrected it, then select all the edges and bevel.
Don't be satisfied with what you can do but rather strive to do the things you can't do!
Exceed Expectations!