I have done some research but without seeing pictures and knowing some specifics about your climate and whatnot I can only get general, so.. in general:
Sandalwood likes lots of sun and temperate rainfall (900-1100 mm/year). They do well within a temperature range of 15-25°C. They prefer soil with a pH around 6. The soil can be somewhat sandy, or rocky.. so long as it has moderate drainage. They dislike waterlogged soil and they aren't meant to grow in a desert; so, somewhere in the middle.
As I stated in the comments they aren't going to thrive without a partner due to their inability to absorb adequate nitrogen from the soil; may I suggest a pigeon pea tree for a life partner?
Protect the little guy: all the herbivores love the sandalwood (for obvious reasons) so its going to behoove you to keep them away from it.
I suspect your problem is revolving around either over or under watering. Based on your description of the soil I am going with over watering. Feel free to add some agents to the plants soil which will help with drainage: