Solver with IF statements

Hi

I am doing a Schoolproject where i am opmizing a portfolio.
I am using the solver to find a optimal mix of assets in a portfolio.
I am trying to get the solver to understand that the expected return for a asset changes when the solver is short selling it.
Since i then have to account for financing costs.

However i don't get it to work, if anyone could take a look in the excel file and see if it would be possible i would greatly appreciate it.

Thanks