It sounds like you've added Ghost Dragon into the Draconic Ancestry table for the Description section of the Draconic Ancestry Racial Trait. To make the Ghost Dragon a selectable Draconic Ancestry, you'll need to do quite a bit more to make it functional.

First, once you scroll a bit further down in the Draconic Ancestry Racial Trait page, you'll see a section for Options:

Clicking on the collapsed group will open up the full amount of current options for your copy of the dragonborn race:

You can click on Add an Option to add a new Ghost Dragon option. (Tip: Clicking Edit on an existing Option will allow you to see exactly how the official versions are set up!)

After adding Ghost Dragon as an Option, you'll have to add more Options to other Racial Traits (both Breath Weapon and Damage Resistance) to create the full functionality of the Ghost Dragon ancestor. I again recommend clicking Edit on existing Racial Trait Options to see exactly how these are set up officially. Be sure to add the following to your Ghost Dragon Options for both Breath Weapon and Damage Resistance:

Once you've set up the appropriate Options in Damage Resistance and Breath Weapon (including the Action and its Limited Use / Level Overrides for the Breath Weapon trait), you should have a fully functional Ghost Dragon dragonborn.1