how to get inline javascript to fire with jQuery

Question

I have a javascript action on a div (asp.net panel) as an onkeypress attribute. This is the default action button on an asp.net Panel control. It contains the following:

onkeypress="javascript:return WebForm_FireDefaultButton(event, 'ctl00_cp1_ucInvoiceSearch_btnSearch')"

For some reason when I change my textbox to a jQuery textbox clicking enter no longer fires this div. Why and how can I hook it back up so when I enter text in the textbox and click enter it fires?

Lloyd