The Incapability Argument - Another ontological argument and the best one yet I think

Premise 1: What must be is
Premise 2: If we can imagine something it is either real or not real
Premise 3: If something is incapable of being the opposite of X then it must be X
Premise 4: If a being that is real is incapable of being not real then a being that is reality is also incapable of being not real.
Conclusion: A being that is reality is real.

Further explanation: I imagine a unicorn. Can a unicorn be not real? Yes. So then a unicorn may be not real but if I imagine a being that is reality can it be not real? No. Because if a being that is real is incapable of being not real then a being that is reality must also be incapable of being not real so I have to presume that "A being that is reality" is real.

In other words, if you imagine something that, by its very nature, is incapable of being not real then it must be real.