I’ve written about the deadline, because it’s an obvious thing that can be easily overlooked. And it’s exactly what happened to you.
I’m afraid here is your mistake. 12 pm means 12 in the middle of the day, whereas 12 am is midnight. Therefore, if you tried to submit your homework at 9 pm you were 9 hours too late (!). 9 pm = 21 (in 24-hour clock time).
Here is the time table:
(Personally I prefer 24-hour clock. There is no such confusion.)
One more thing: as far as I remember an official and the only language at this forum is English, so please follow the basic rules. And if you want to send me private message use this option on my account:
Also, this sentence in Polish has no sense to me.