I commend you to read Why isn't CVX accepting my model? READ THIS FIRST! . , CVX does not allow different variables to be multiplied togetherm except when in gp mode, whicg comes with its own special restrictions.
Have you forgotten Cannot perform the operation: {real affine} .* {convex},but i don't use the `.*` ? You have violated CVX’s rules, so you get an error message. The error message is not always that informative as to what the actual offending item is.