Ajax :: Firefox Call Fail ?

I have an Ajax call and it keeps return nothing versus some text when the ready state is 4, and the status is 0 inside Firefox 3.6.

I debug the server and it did return some text. The browser just doesn't expose it.

The JSP code is in a Weblogic server in port A, the JS code is included in the JSP coming from Weblogic port B (2nd server, same host). The Ajax call URL is on the same Weblogic server/port B as the JS. The Ajax call is started from a click on a button from the JSP page serving on port A).

Here are the configurations that works with the identical code:

1) Exactly like above using Internet Explorer

2) Exactly like above using Firefox, with the exception that the server is OC4J versus Weblogic

3) Exactly like the above (Weblogic), with the exception that the JSP and JS codes are in the same (single) server/port and using Firefox browser

So this is very strange. The same Weblogic server would work if all files are in a same server. In any case, the server code always work, and always return valid value (I wonder if some header is different). In fact IE works.

I think it's maybe security issue of Firefox handling of 2 servers. However, the same Firefox does work with OC4J servers.