schefflera losing leaves
 

Hi:
I have an indoor gold capella schefflera plant, and
its leaves are falling off quickly. I water it once a week,
place it near a window with bright sunlight. The leaves falling
off are kind of brown and withered.
Could someone tell me what I am doing wrong? More watering?
I also have another schefflera plant (just green leaves). This
plant is placed near the above gold scheffelera, receives the same
watering schedule+amount, and it thrives!!

Thank you,
Minh