Terrarium plant dying

Hi, I have a question I just learned the name of a cute little plant that is in a simple terrarium that I received for Mothers Day. Its a Muehlenbeckia Axillarist it's dying. My question is what am I doing wrong? Is this a good plant for a terrarium? What can I do to correct it? I usually have the jar top open, should I close it?Thanks much in advance.

I had this plant but not in a terrarium. It died as well. Here's a bit more info: http://davesgarden.com/guides/pf/go/58078/

Thanks so much Cville. I'm afraid it is just one of those tender plants that doesn't survive my grandchildrens attempt at watering and caring for Memas plants. God love 'em. Thanks again! #1-2 before and #3-4 after :(