train schedule from LaSpezia to Pisa

Those trains are running. The "NA" simply means that they cannot be booked online for that particular date. (In your case that is irrelevant anyway because the Trenitalia site does not accept US credit cards.) Enter a date within the next few days and the fare will show and the "NA" will disappear.

Thanks Tim, but I wasn't planning on buying, just checking the schedule to make sure I could get to Pisa on time. I checked the day before and the day after and they all said N/A for the early trains. Must just be one of the things.

You're welcome, Susan.

Actually, it's not "just one of those things." For regional trains you must enter a date within seven days from today in order for the fares to appear. The reason for this is that online booking for regional trains (for those whose credit cards work on the Trenitalia site) can only be done up to seven days in advance while booking on long distance trains can be done up to 90 days in advance. For example, I just got fares for the early regional trains up to and including 14 June, but as of 15 June the "NA" message appears.

as a side note, be REALLY skeptical about whatever the schedule says for trains in that area. I'd add at least an hour. We took one from Monterosso to La Spezia that was about 40 minutes or so late (for a trip that should have only been 30 minutes anyway) and I cursed myself for not getting on the train an hour earlier than what the trenitalia site said I should take. They don't account for delays AT ALL.

Thanks for the clarification Tim! It makes much more sense now.