[Scenario]

This is hard to figure out unless we have your whole script, if you want, send me your script/includes/plugins in a PM, and I will take a look.

But This is what I have so far...

Код:

main()
{
  print(" (v1.0) BasicAdmin loaded");
}

#endif

public OnPlayerText(playerid, text[])
{
  if(PlayerData[playerid][Muted] == 1)
	{
    SendClientMessage(playerid, COLOR_RED, "You are muted and cannot talk.");
    return 0;
  }
  return true;
}

You were missing [] after Text.
And had a ( instead of {