[Zope] validation-onClick

The form="a" and its input field="custid" is being validated, when the alert message box came out then i clicked on the 'OK' button which is inside the alert message box, but it return to another page instead return to form="a". ( I prefer to use 'onClick' instead of 'onSubmit' ) The following is my JavaScript validation function:- function checkid() { if(document.a.custid.value==""&&document.a.custname.value=="") { alert("You must specify string character either in customer id or customer name.") document.a.custid.focus(); return false; } } The form events:- <input type="SUBMIT" name="Search" value="Search" onClick="JavaScript:checkid()" >