Love to help you out with your Prop. You should have two different parts, one that says "PROP" and one that reads, "MAKE Collaboration" on the rear loop. If so, you should press the two pieces together firmly at the joint until they are interlocked. Here's a good photo of what it should look like!
Here's also an Unboxing video:
Unboxing a Prop from MAKE Collaboration
We do from time to time have Props that aren't made correctly and get through our quality assurance without being detected. If so we'll gladly work with you to get an exchange or refund.