Why can't the compiler properly detect the type of Array!string("something")?

[Adnan]

In the following code the compiler says the type is 
Array!()(string):

			if (key in wordTable)
				wordTable[key] ~= word;
			else
				wordTable[key] = Array!string(word);


source/app.d(29,36): Error: template 
std.container.array.Array!string.Array.__ctor cannot deduce functi
on from argument types !()(string), candidates are:
/snap/dmd/99/bin/../import/phobos/std/container/array.d(467,5):   
      __ctor(U)(U[] values...)
   with U = immutable(char)
   must satisfy the following constraint:
        isImplicitlyConvertible!(U, T)
/snap/dmd/99/bin/../import/phobos/std/container/array.d(501,5):   
      __ctor(Range)(Range r)
   with Range = string
   must satisfy the following constraint:
        isImplicitlyConvertible!(ElementType!Range, T)