prop change

[Joker2]

I purchased a new prop Michigan wheel vortex ,it came with a hub kit, when I went to change the prop, I put it all together and the washer that goes on after the prop ( the one that is about 3/8" thick and has grooves to interlock with the splines ) doesn't catch any splines. The splines end flush with the end of the hub assembly. Did everything the way the instructions aid to do, they reference using the old washer and they show it in the diagram but it looks much thinner ( like a regular washer ) can I go to a marine store to get this washer, without it the prop just slides right off. This is the type of setup i have now. Thanks