Really, the only time a joint breaks (especially a finger joint - that's some serious joinery), at the joint, is if there isn't enough. Enough what? Here's a short list - glue, pressure, long grain, drying time, clamping time, etc.
There are many who agree that a glued joint is stronger than wood. I've experienced this, first hand. Glued joints don't break, if glued properly.
If it were my guess, yours is a combination of things, lack of glue being the first. The grain on the neck is not vertical, so there's probably some end grain in the glue joint somewhere - this would also be a contributing factor.
I'd send it back. -Aaron