Limit the attachment to a ListItem of Custom List

I have a Custom List. When the user adds a List item they can attach some attachment to the list. I want to limit the no. of attachment files attached to a List item. I wrote one event Receiver and Override ItemAttachmentAdding. But the event is not firing when an attachment is added.

Please anyone help to achieve this.

Thanks in advance.

Regards

R.Mani