[Scenario]

The error has to be caused by something else- seems fine to me.

That isn't working because of this:

pawn Код:

if(sscanf(params, "{s[7]}dd", iNoteID, iNoteSlot)) return SyntaxMSG(playerid, "/note give [playerid] [slot]");

You didn't change the first d specifier, so it looks for a numerical value, not a player ID/name. So, change the first d specifier to u, and change iNoteID to iTargetID.