Problems with midi imput

Hello everybody,
I'm using a midi keyboard to insert the score, but I have a problem:
when I use the real time automatic input when I press the keys they clog themselves into an unique "chord" instead of one per time as in the photo.
Plus the chord remain even if I stop pressing the keys and it continues until I stop the recording.

But when I start a new score without anything as instrument or key, this doesn't happens, because I tried to insert into a score with an instrument but happens again.

I think that mayby I pressed something on my keyboard or changed some setting of musescore.

THX a lot for every help given