That's quite correct if the VGA port is not connected to an active VGA output of a laptop or PC, and the monitor is not connected to an active hdmi, DVI or whatever else signal it can receive either.
Nothing in your post says it's otherwise.
Im using an Asus monitor , and everytime i turn it on it says no vga signal . And some there is no input select button on my monitor . Cant switch to other input

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