Transactions can only be made from the accounts page. All contacts in the address book are read-only and no transactions can be made from them. 

You will only see your Ledger account on the accounts page when your Ledger device is connected to your computer. So if you want to make any transactions, then you need to attach the device. Whenever it is not connected, the accounts page will "forget" your Ledger account.

If you simply want to check your balance, then you can view your Ledger account in read-only mode on the contacts page in your address book. It will remain there even when the device is not connected.

Here is more information to help you understand the difference between the accounts page and the address book.