Problem remote dubugging javascript in a JSP

I have a problem with debugging a javascript in a JSP. I am using IntelliJ 8.1, tomcat, and a remote debug configuration.
I have a table with checkboxes and want to debug the javascript code activated when one of the checkboxes is selected. My javascript code looks as follows:

<script language="javascript">
    function checkboxChanged(index)
    {
    alert(index);
    document.f1.edit.disabled=false;
    document.f1.del.disabled=false;
    }

</script>
...

<td><input type="checkbox" name="check" onChange="checkboxChanged(<%=i%>)"> </td>

I put a breakpoint on the alert line. I start tomcat configuration which opens the JSP page as the launch page. I close the page, and start the remote javascript debug configuration. The breakpoint is hit (!). I hit F9 and the embedded browser opens. Then I select one of the checkboxes in the table. I get the alert, but the breakpoint is not hit! Any idea why this is happening?
Thanks in advance.
Yacov