Works for me:
DDgui_pushdialog(10,10,220,220)
DDgui_checkbox("ch1", "readonly?")
DDgui_button("bt1", "Button")
DDgui_automate("ch1", "SELECT", "bt1", "READONLY")
WHILE TRUE
DDgui_show(TRUE)
IF DDgui_get("bt1", "CLICKED") THEN DDgui_msg("Bing!", FALSE)
SHOWSCREEN
WEND