Hi Experts -
this.getField("checkbox 1").checkThisBox(0, (event.value!=""));
A LiveCycle form has a different object model than an Acroform. You might want to start with this information LiveCycle Learn & Support .
TextField1.isNull ? 0 : 1;
(You don't need a return keyword)
This assumes you haven't change the default checkbox values of on/off from 1 and 0.