Why does this not pass

[Imperatorn]

Why does all these pass:
     static assert(is(ElementEncodingType!(char[]) == char));
     static assert(is(ElementEncodingType!(wstring) == 
immutable(wchar)));
     static assert(is(ElementEncodingType!(byte[]) == byte));
     static assert(is(ElementEncodingType!(ubyte[]) == ubyte));

     auto range = iota(0, 10);
     static assert(is(ElementEncodingType!(typeof(range)) == int));
     static assert(is(ElementEncodingType!(immutable(ubyte)[]) == 
immutable(ubyte)));

But not this:
     static assert(is(ElementEncodingType!(AsciiChar[]) == 
AsciiChar));