AppDesigner : How to Change the value of a dd according to the user input to another dd?

I am trying to build a GUI, one of the functionalities needed is when a user change a value in one dropdown list, I want another dropdown list to change to a certain value at the same time: if user chooses Option 2 from dd 1 then dd 2 should show Option 3. Please note both dd have same Items (dd1 has option 1. option2, option 3 and dd 2 has same items), this function should not tweak or change any of the dd items. Any ideas on how to do so? What to replace the "???" with in the following: (I know switch/case might work instead of the if-else)

 function  Changedd2whenddchanges(app)
            value = app.DropDown.Value
            if value == ('Option 2')
                app.DropDown2.???== ('Option 3')
            end

        end

Thank you :)

[Geoff Hayes]

kmoust - wouldn't it simply be

 app.DropDown2.Value = 'Option 3';

I don't have AppDesigner so this might not work...

[kmoust Taf]

did not work. I tried it already.

[Geoff Hayes]

what happens when you try that? what error do you get? please show your code and the full error message.

[Adam]

Are you sure you didn't get it wrong and use the == that you have included in your code above instead of = ?

[kmoust Taf]

After troubleshooting the problem was not in the function, there was no error when running, turned out in appdesigner I have to create the function, and then create a callback function in which I can call the function.