well thats because the manga ended similiar to the anime... there are differences but both ended like this.
no real answers given etc.

they wanted to wait a bit probably? or thought "well since there is no manga, there is also no material to use"... i don't know how those people work if they make an anime out of a manga.
but i thought they only use what they have and since there is nothing to use, they dropped it as "finished" or something like that.

probably, just probably, when the manga is finished or has more volumes, they will make a sequel
if dreaming is allowed i would like to continue this dream