Is this (Wii) Guitar Hero controller normal?
Solution 1:
Behold the Guitar Hero World Tour guitar for the Wii: 
AKAIK all first party guitars had colors on the solo section of the neck, not colored dots on the side. Spending the past 30 minutes, I can't even find a guitar neck that matches that style, so I can't say exactly what it's for.
But really, it all boils down to simply ensuring that it doesn't fit. Orient the neck properly and try to slide it down. If it doesn't fit then it doesn't fit, and it's time to contact the seller.