Why are the leaves on our new desert rose plant continuing to fall off?

We purchased this plant at Lowes about one month ago. We moved it indoors and out of direct sunlight to our living room that is bright at least 6 -8 hours a day. It also gets brighter indirect sunlight that occurs between 3PM-- 5PM. Since we got this plant the leaves continue to drop off. What are we doing wrong? We water it when it is dry, but not dusty dry & are frustrated with watching the leaves fall off. We have not given it any liquid plant food as yet. Each day we see another leaf getting ready to fall off this lovely plant. The indoor temperature of our home is 75 degrees F.
Asked May 28, 2010
Edited May 28, 2010

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