Den seedling turning brown

[Chococatte]

I gotten some Den antennatum seedlings, they were already shipped out of flask, I did everything that was recommended too me. Only thing though I didn't have clam shell food tray kind you get from Walmart hot food bar, so I put the Den seedings in a Ziplock food container with some moist sphag moss (not soppy too wet). Keep the lid close for a week, start opening the lid for gradually for a hour or so that the 'chids could get some air circulation. I was checking on them today and some of the 'chid leaves have turned brown. What do I do now I don't want to loose all my baby 'chids to rot? **Note: I have them on the table outside (look @ my gallery for ref) where my other adult orchids grow.