Guisetctlvalue reported "Item not found matching the value of xxxx

DO 
  guisetctlvalue()	 
  CATCH SYNTAX
    NOP
END

/*

GUIBEGIN

WINDOW , 0, 0, 220, 86, POPUP|CAPTION|SYSMENU|MINBOX|MAXBOX|THICK, , My Window
	FONT 8, 400, MS Shell Dlg
	LIST 14, 34, 181, 29, NOTIFY|SORT|BORDER|VSCROLL|TABSTOP, INDEX, service_list
	PUSH 174, 70, 40, 14, TABSTOP, , select_button, , Select
	ENTRY 59, 9, 32, 12, H_AUTO|BORDER|TABSTOP, , field1_entry
	ENTRY 135, 9, 67, 12, H_AUTO|BORDER|TABSTOP, , field2_entry
	TEXT 17, 10, 20, 8, GROUP, , , , Field1
	TEXT 104, 12, 20, 8, GROUP, , , , Field2
	PUSH 120, 68, 40, 14, TABSTOP, , add_button, , Add
DEND
GUIEND

*/
OPTIONS "C_CALL LABELCHECK"
NUMERIC DIGITS 10
DO
	RXFUNCADD('rexxgui')
	CATCH FAILURE
		CONDITION("M")
		RETURN
END
line_nr = 0
service.0 = 0
guierr = "SYNTAX"
guiheading = 1
guicreatewindow('NORMAL')
again:
DO FOREVER
	guigetmsg()
	IF EXISTS('GuiObject') == 0 THEN DO
		IF EXISTS('GuiSignal') THEN DO
		END
	END
	ELSE DO
		IF EXISTS('GuiSignal') == 0 THEN DROP (guiobject)
		ELSE SELECT guiobject
			WHEN 0 THEN NOP
			OTHERWISE
		END /* SELECT GuiObject */
	END /* Some child script signaled us */
	CATCH SYNTAX
			CONDITION('M')
			SIGNAL again
	CATCH HALT
	FINALLY
		guidestroywindow()
END
RETURN
wm_click_add_button:
line_nr = line_nr + 1
new_service = 'Added line_'line_nr
service.0 = service.0 + 1
service.line_nr = new_service
err = guisendmsg('service_list', 'ADDSTRING', ,new_service)
RETURN
wm_click_select_button:
guigetctlvalue('service_list')
i = service_list + 1
temp = service.i
PARSE VAR temp field1_entry field2_entry 
CALL delete_service()	
guisetctlvalue()	 
RETURN	
delete_service:
temp = service_list + 1
temp_name = service.temp
guiremovectltext('service_list', '')
ERROR = STEMDELETE('SERVICE', , temp, 1)
RETURN