I have some phals in moss and bark mixture too. The trick is don't water until the moss is crackling dry. Or you can do moss in clay pots, which is a much safer bet, because clay pots allow more air circulation and the moss dries out faster. But plastic or clay, you don't need to water until the moss is crackling dry.
Potting in bark is completely fine. The orchid only suffers because the bark has not been broken in. To aid that process, I put the bark in a bowl of water and microwave it for two minutes. It seems to aid in breaking the bark in.
Also, after repotting in bark, make sure the environment is more humid or you can mist spray in the morning.
Here are some pics of my Phals in bark and moss mix...
Andrew