The relationship that you are using as the basis for your value list relationship requires that you also specify a trail ID. If that field is empty, you won't get any values as you won't have any matching records. If you also select a Trail ID, you'd get exactly one value--so just entering a Trail ID isn't going to work either.
In order to get a list of trails for a given park, you need a relationship that matches only by Park ID. To do this, you need to either modify the existing relationship, or add a new occurrence of the Trail Info table so that you can both link to it only by Park ID and also use it as the source of values for your value list.
I see that both of your Value Lists are based on the same table "Trail info". I think the second value list should be showing data from the Point of Interest TO.
Thank you!! I knew I was missing something fundamental, that makes perfect sense.