Well, not an expert here, but here's what I know about Japanese Maple care. (And why I can't grow them here.)
They prefer slightly acidic soil, with a pH of 5.5 to 6.5.
Soil needs to be "well drained".
They like consistent moisture with regular watering.
Part shade is best, with protection from wind.
I suspect that your conditions are just not right for this particular tree, and recommend that you try something else.
