Tell me why

Question

下面的代码为什么出错?procedure TForm1.Button1Click(Sender: TObject);
var
t:int64;
i,n:integer;
begin
t:=1;
n:=strtoint(trim(maskedit1.Text));
for i:=1 to n do
t:=t*i;
label1.caption:=inttostr(t);
end;procedure TForm1.FormCreate(Sender: TObject);
begin
maskedit1.SetFocus;
end;procedure TForm1.MaskEdit1KeyPress(Sender: TObject; var Key: Char);
begin
if key=#13 then
form1.Button1Click(form1.Button1 );
end;

Answer 1

maskedit1.SetFocus;
窗体创建时maskedit1还没有生成！
在onshow事件里写吧

Answer 2

将maskedit1.SetFocus;放到formonshow事件中

Answer 3

form1.Button1Click(form1.Button1 );
错误
button1.click;

Answer 4

if key = #13 then
    Button3.Click ;

Answer 5

if key = #13 then
    Button1.Click ;