Could not resolve Spring property placeholder

I have my config:

<context:property-placeholder location="classpath:idm.properties" />

<bean id="idmPropertyHolder" class="fi.utu.resurssitilaus.idm.IdmPropertyHolder">
   <property name="url" value="${idm.url}" /> 
    <property name="user" value="${idm.user}" />
    <property name="password" value="${idm.password}" />
    <property name="proxyHost" value="${http.proxyHost}" />
    <property name="proxyPort" value="${http.proxyPort}" />
</bean>

I get the error

    SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
    org.springframework.beans.factory.BeanDefinitionStoreException: Invalid bean definition with name 'idmPropertyHolder' defined in ServletContext resource [/WEB-INF/idm-config.xml]: Could not resolve placeholder 'idm.url'
            at org.springframework.beans.factory.config.PropertyPlaceholderConfigurer.processProperties(PropertyPlaceholderConfigurer.java:272)
            at org.springframework.beans.factory.config.PropertyResourceConfigurer.postProcessBeanFactory(PropertyResourceConfigurer.java:75)
            at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:640)
            at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:615)
            at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:405)
            at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:276)
            at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:197)
            at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47)
            at org.apa