enable/ disable a text input field based on checkbox choices.

I want to manage the video length input field to be disabled if the user choose only photography,

and enabled if the user choose:

1- videography

or

2- both(videography and photography).

However, I have attached the code i have used and it is not working, please share your thought about what could be the problem.

Thanks,

export function ServiceType_change(event) { if ($w("#checkbox1").checked){          $w('#VideoLength').disable();} else{$w('#VideoLength').enable();} }