progress 4gl - setting a label after define -

i have display statement , display 1 of values if logical true. how can not display label of column (ie. blank)

 def var 1 char label "one" no-undo.  def var 2 char label "two" no-undo.  def var 3 char label "three" no-undo.  def var 4 char label "four" no-undo.  def var logic logi no-undo init no.   display      1    2    3    4 when logic  stream-io width 80. 

define variable 1 character no-undo initial "xyz". define variable 2 character no-undo initial "123".  define variable f handle no-undo. define variable h handle no-undo.  form   1 2  frame .  f = frame a:handle.  if 2 = ""   do:     h = f:first-child.     walk_tree: while valid-handle( h ):       if h:name = "two"         do:           h:label = "x".           leave walk_tree.         end.       h = h:next-sibling.     end.   end.  display   1 2  frame .