OpenEuphoria

To display a series of 64 items at specific locations, I need to pick a series of formatting information from a long sequence. The original matrix, for use with printf, looked like:

rn_display_format = 
    { {  0, 35, "%12s", 1, 0, 12}, 
      {  1, 16, "%12s", 2, 0, 12}, 
      {  1, 58, "%12s", 2, 1, 12}, 
      {  2, 6,  "%12s", 4, 0, 12}, 
      {  2, 26, "%12s", 4, 1, 12}, 
      {  2, 48, "%12s", 4, 2, 12}, 
      {  2, 68, "%12s", 4, 3, 12}, 
      {  3, 1,  "%8s", 8, 0, 8}, 
      {  3, 11, "%8s", 8, 1, 8}, 
      {  3, 21, "%8s", 8, 2, 8}, 
      {  3, 31, "%8s", 8, 3, 8}, 
      {  3, 43, "%8s", 8, 4, 8}, 
      {  3, 53, "%8s", 8, 5, 8}, 
      {  3, 63, "%8s", 8, 6, 8}, 
      {  3, 73, "%8s", 8, 7, 8}, 
      ... etc. 

My test of extraction from a sequence for use with display is:

include std/io.e 
include std/filesys.e 
include std/error.e 
include std/console.e 
include std/graphics.e 
include std/sequence.e 
include std/cmdline.e 
include std/convert.e 
integer key_code, start_number, stop_number 
sequence test_sequence = "123456789" 
sequence display_portion, format_string, slice_start, slice_stop 
clear_screen() 
position (4,20) 
format_string = {1,2,3,4,5,6,7,8,9} 
slice_start = slice(format_string, 4,4) 
start_number = to_number(slice_start) 
slice_stop = slice(format_string, 9,9) 
stop_number = to_number(slice_stop) 
display_portion = slice(test_sequence, start_number, stop_number) 
display(display_portion) 
key_code = wait_key() 

There are no error messages, but it displays the entire string
123456789
whereas I expected
456789

What's wrong?