一个ABAP初学者的问题

大家有没有ABAP的QQ群介绍下。

顺便问个小问题。

code

   report  z_helloworld.

tables:spfli.
selection-screen begin of screen 100 as subscreen.
  selection-screen begin of block a1 with frame title text-A01.
    select-options mat1 for spfli-carrid no intervals.
    selection-screen skip 1.
    parameters chk1 as checkbox default 'X'.
    selection-screen end of block a1.
    selection-screen end of screen 100.
    selection-screen begin of screen 200 as subscreen.
      parameters mat2(20) type c.
      selection-screen end of screen 200.
      selection-screen: begin of tabbed block mytab for 5 LINES,
        tab (20) button1 user-command ph1,
        tab (20) button2 user-command ph2,
        end of block mytab.
        initialization.
        button1 = 'TAB1'.
        button2 = 'TAB2'.
        mytab-prog = sy-repid.
        mytab-dynnr = 100.
        at selection-screen.
          case sy-ucomm.
            when 'ph1'.
              mytab-dynnr = 100.
              mytab-activetab = 'button1'.
              when 'ph2'.
                mytab-dynnr = 200.
                mytab-activetab = 'button2'.
                endcase.

/code

帮忙看下这段代码哪里有问题啊。结果不对。