Adding a mandatory checkbox in iExpense

Hello

I have a requirement to add a Checkbox and make it mandatory.

My requirement is on the final page where the Manager approves a Expense Report, I want to create a checkbox that the manager agrees to compliance policy etc... Only if the checkbox is checked, he should be able to hit the Approve button.

So, I made the checkbox mandatory. However, still I am able to hit the approve button and it seems like the checkbox is not mandatory.

Any ideas on how to pull this off ?

Thanks

Len