phal roots drying/rotting?

[dianchik001]

Hello,

I am new to this site. I absolutely love orchids, especially Phalaenopsis , however i have had three and none of them survived and i dont know what im doing wrong.
this is my latest one...
its planted in bark, no spag at all, have trimmed the roots that were dry/dead. the roots on the pic are silver/green. sometimes they are just silver, do they need more water when they are silver as suppose to green??. i currently keep it under another plant so it gets moisture, position is close to the window, only gets morning sun, nothing too hot.

any suggestions would be much appreciated!