Have your continue button perform a script such as:
Set Error Capture [on]
If [Get ( LastError ) > 0 // an error occurred committing the record ]
Show Custom Dialog ["Please make sure that all required fields have data]
Go to Layout[//specify next layout here]
You might also use conditional formatting to automatically highlight all required fields or you can use a more sophisticated script that checks each field in turn when there is an error returned by Get ( LastError ) and puts the focus (cursor) into the first such field found to be empty.
Excellent, thank you.