We are traveling from Marne la Vallee Chessy to Carentan via train for a day-trip to Normandy in June. I have been to the bahn.com train site and can see all the tickets I want to purchase, but there is a "Fares not Available" in the pricing area. I'm really concerned about not having seats, but can't figure out how to buy these tickets! Help!
You can't buy French train tickets on the website of the German national railway. Go to www.capitainetrain.com which is an agent for French national railway, but has an easier ticket buying process than the en.voyages-sncf.com
I don't see any fast TGV trains serving this route. You normally take the local Paris RER to Auber station then walk to Gare St. Lazare for a regional train to Carentan. These trains cannot sell out, but they do offer seat assignments when you book ahead.
The Bahn website is great for schedules for almost all of Europe. But it only gives prices and sells tickets if the train starts or ends in Germany. For other countries, you usually want to first try to buy from the website of the country the train originates in. Here's a list from that train guru, The Man In Seat 61: http://tinyurl.com/bo8x6o6
The French train site shows lots of departures for your destination leaving the Disneyland station. Not direct, though, with two changes of train and a duration of more than six hours. The site is http://en.voyages-sncf.com/en/ Specify ticket pick-up in a country outside North America (I choose Antarctica, for a giggle) and be sure to uncheck the Direct Trains box.