Why is autowired properties file null?

I autowired some beans from my testConfig.xml, and it works fine but when I want to autowire a properties file it gives null, the properties file is near of my xml in selenium folder. My testConfig.xml looks like this :

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://ift.tt/GArMu6"
    xmlns:xsi="http://ift.tt/ra1lAU"
    xmlns:context="http://ift.tt/GArMu7"
    xmlns:util="http://ift.tt/OGfeTW" 
    xsi:schemaLocation="
        http://ift.tt/GArMu6 http://ift.tt/GAf8ZW
        http://ift.tt/GArMu7 http://ift.tt/1bGeTcI
        http://ift.tt/OGfeTW http://ift.tt/1aj0W5e" >

    <bean id="base" class="java.net.URI">
        <constructor-arg value="http://localhost:8080/MySite" />
    </bean>

    <bean id="siteBase" class="java.net.URI">
        <constructor-arg value="http://localhost:8080/MySite/site" />
    </bean>

    <bean id="adminBase" class="java.net.URI">
        <constructor-arg value="http://localhost:8080/MySite/admin" />
    </bean>

    <bean id="firefoxDriver" class="org.openqa.selenium.firefox.FirefoxDriver" destroy-method="quit"/>

    <context:annotation-config/>
    <util:properties id="seleniumSelectors" location="classpath:selenium/selenium-selectors.properties"/>
</beans>

and here I want to autowire it:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "/testConfig.xml" })
public abstract class AbstractUITest extends TestCase{


    @Autowired
    protected URI base;


    @Autowired
    protected URI siteBase;


    @Autowired
    protected URI adminBase;


    @Autowired
    protected WebDriver firefoxDriver;

    @Autowired
    @Qualifier("seleniumSelectors")
    protected Properties selectors;

Just the selectors object is null and I don`t know why, any suggest?