JSF 2.0: Empty operator doesn't work with param

In the file `aPage.xhtml`, I have the following lines: ``` <ui:include rendered="#{not empty param.target}" src="#{param.target}.html" /> <ui:include rendered="#{empty param.target}" src="About.html" /> ``` With the above lines, I expected that when I go to `http://localhost:8080/beta/aPage.xhtml`, the page `About.html` would be included since the `param.target` is `null`. However, GlassFish threw me the following exception: ``` java.io.FileNotFoundException: http://localhost:8080/beta/.html ``` Somehow, `param.target` was not considered to be `null`. Besides, I did try to use `==` and `!=` operators as following: ``` <ui:include rendered="#{param.target != null}" src="#{param.target}.html" /> <ui:include rendered="#{param.target == null}" src="About.html" /> ``` Interestingly, this time, on the console of GlassFish, I didn't see any exception thrown. However, on the browser, an error page still appears with the exception `java.io.FileNotFoundException`. I'd be very grateful if you could tell me why this happened and what I should do to avoid it. UPDATE: Thanks to the hint from Joop Eggen, I finally solved the problem with the following lines: ``` <ui:param name="noTarget" value="About.html" /> <ui:param name="hasTarget" value="#{param.target}.html" /> <ui:include src="#{empty param.target? noTarget : hasTarget}" /> ``` Best regards