Bush Allamanda schottii problem

[aykhan]

I got the bush variety of Allamanda which the nursery said they had imported from Thailand. Very beautiful with profuse yellow flowering. I killed two of these last year but this year when I saw it for sale I was tempted again! I put it in a pot with peat moss, compost and some super phosphate. Watered it well and have put it in full sun about 6 hours maybe. However, it is doing the same thing my other two did last year before dying ie the leaves are turning yellow and it's looking ill. The two which dies last year were in the ground. What could possibly be going on??? Here are the pictures. Sorry iphone pictures this time.

[Izhar]

It looks to me as it has been in wet feet.. nowadays bush allamandas are flowering here profusely

[aykhan]

I have a well draining medium. Do you suggest I let the bush completely dry out for few days before watering?

[Izhar]

Yes, but if the rotting has started already in the roots then it wont survive, it should be re-potted in plain soil with low moisture holding capacity...