Why didn't the Potters disapparate?

[Lisa]

No: HPFGUIDX 23162

This may sound like a really obvious question, but why didn't Lily and 
James just disapparate when Voldemort showed up?  From other instances 
of apparation, it seems that whatever the person is 
holding/wearing/carrying will apparate along with them.  So Lily could 
have simply grabbed Harry and disapparated with him, and James could 
have done the same.  Of course then I guess there wouldn't have been a 
story, would there? :)