That is a possibility, but I;m not sure if it is the only possibility. You should look at cvx_status, which will indicate whether the problem is infeasible, or perhaps has failed for some other reason (solver difficulty).
BTW, I’m not a professor. I’m just a random Joe Blow (as we say in the U.S.) who happens to have read CVX’s documentation.http://cvxr.com/cvx/doc/ and Why isn’t CVX accepting my model? READ THIS FIRST! and used CVX a bit.