Magento 1.9.2.4. Error when creating child theme

Error when creating child theme: the custom styling and some basic functionality are missing. Any ideas what is still going wrong?

app/design/frontend/theme/custom/etc/theme.xml

< ?xml version="1.0" ?>

    theme/default
    
        
            
                custom.xml
            
        
    

Next:

app/design/frontend/theme/custom/layout/custom.xml

< ?xml version="1.0" ?>

    
        
            skin_csscss/custom.css< ![CDATA[]]>
        
    

Styling created at skin/frontend/theme/custom/css/custom.css

Configuration adjusted in System -> Configuration -> General -> Design -> Package

Current package theme: theme

Next:

Configuration adjusted in System -> Configuration -> General -> Design -> Themes

Templates: custom
Skin (Images/CSS): custom
Layout: custom
Default: default