Soft shaft,hard glans and Corpus Spongiosum

I am one of the guys who, when they get erected the glans are not getting hard,but are as they were flaccid(same situation about the corpus spongiosum). I don’t know if the reason of that is chemical or mechanic,but I suspect that if the reason is the chemical one, then maybe different chemicals stimulate the corpus spongiosum-glans than Corpus Cavernosum inflammation ,so the guys with the soft Corpus Cavernosum-glans(during erection) maybe had a problem with the second group of chemicals.But If this is true,then maybe there is the opposite situation in which somebody ,sometimes ,can have his glans get erected and truly hard but not his shaft( Corpus Cavernosum) . So ,is there anybody ,who has been to this situation,(hard glans but not shaft)?