if i click on a <li>-Element, it's children should be displayed

This works fine but if i click on the back button and let me display the same Elements again, the code fails

(try 1 > back > 1 in the jsfiddle)

here's a jsfiddle with code i created

i don't have a cule what i'm doing wrong here 

(perhaps there is even a more elegant way to deal with it than parent() and children())

thanks in advance,

Fiisch0r