Explain more of where you have your code and what you’d like to happen. That will help us help you.
LotusScript does not work on the web. LotusScript runs in the Notes Client and on the Server. If you code is in a button, you’ll need to either use JavaScript to assign the value or convert the LS in the button to an agent.
If you want a Date Picker or Date validation, you must use JavaScript on the web page. There are many sources on the web, use your favorite web search tool.