Navigation Vertical tree Issues

Hello  Team,

I  Have Following requirement,i.e I am using the

 Navigation widget --> Custom Page --> Vertical Sub tree ,I  Had Following requirement  

 1)   Services  ||__  ( Parent)

                IT Services||__(Child Page)

                          App Dev Maintenance ( Sub Child Page)

By Default , Home is There in that All  Navigation tree Showing Perfectly ....When I click on  App Dev Maintenance ( Sub Child Page ), It Navigate to That Page But here Comes any issues,I lost all of My  Child and Sub Child Page   In that Parent .Why it Happens How Prevent that ,Like Home Page I got full tree Same way I need in the ( App DeV Maintenance ) Sub Child Page.

Thanks  & Regards,

Sairam Pamidi.