Required fields validation not working

Hi. In the donation form (site), if I leave any of the required fields empty I don't get error message at all. Have I missed something?

Thank you

Hi,
Please open each Custom field in Joom Donation and check the field: Validation rule to see if the value of that field is
validate[required]
Thanks
Dam

The validation is made if the field is characterized as required but that alone is not enough. I need to have Load JQuery "on". Then in the donation form the fields validation works fine. Still in the backend if I try to enter a donor no validation is made at all.
Thank you