check Box in drop down list flutter

I am using check Box in drop down Menu but when I chose the box nothing change unless closing the menu and open it again here is my code

items: [
DropdownMenuItem(
child: Row(
children: <Widget>[
Checkbox(
onChanged: (bool value) {
setState(() {
isSat = value;});},
value: isSat,),
Text(
daysList[0]['days'],),],),),
DropdownMenuItem(
child: Row(
children: <Widget>[
Checkbox(
onChanged: (bool value) {
setState(() {
isFri = value;});},
value: isFri,),
Text(
daysList[6]['days'],),],),)
].toList(),
onChanged: (value) {},),