Help!How to express the multiplication of two variables in CVX?

Excuse me! In my program,Y1 and Y2 are shown below.I want to express the product of Y1 and Y2. When I use .* ,It threw an error, how should I express it? Can you give me some advice?
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This is the error.
微信图片_20220522090137

That means Y2 is concave and my model cannot be accepted by CVX?Then how can I solve it?

Have you proven it is a convex optimization problem (as directed by the link)? If not, then use a non-convex solver, such as available under YALMIP.