UObject cannot validate an argument I pass it using FObjectFinder.

I’m trying to just change the basic animation flipbooks in the C++ 2D Sidescroller template to get started with this engine. My code is as follows:

However I am getting the error:

I have been following a tutorial on how to do this and cannot see anything immediately wrong with my code.
I know this might be a nooby question but I cannot find any resources online for this problem.
Thank you