Phalaenopsis Orchid flowers withering?

[norg.]

Hey guys. Im very new to keeping orchids and my first orchid is showing signs of distress. Ive had it for around 3 weeks and it has lost 2 flowers already and another 2 are withering. I have been extremely busy with my work schedule so I havent been able to read up on orchids as much as I would like to in the last couple weeks. So thats why Im coming to you!
I water the plant once a week just so that the soil is moist. The light is a 60 watt incandescent bulb in a can light fixture. The room has a adequate air flow, the temperature does however drop to around 65 degrees or so at night. That is about all the background information I can think of... What am I doing wrong?

Also, I tried to post pictures from photobucket and it says they are denied?