Woldemort Type can't even call "take" or "array"

[kerdemdemir via Digitalmars-d-learn]

auto outputString = (char[][] inParam) =>
      (inParam[0].length == 0 || target.startsWith(inParam[0])) &&
      (inParam[1].length == 0 || target.endsWith(inParam[1]));
											
											
auto numArr = threeDArr.filter!(a => a[0].canFind('?')).
		filter!(a => outputString(a[0].split('?'))).
		map!"to!int(a[1])";	

writeln(numArr);	

		

I don't want to get into details of my code and bore you.It takes 
a 3d array like below:

[["201212?4", "64"], ["20121235", "93"], ["2012123?", "87"], 
["2012?234", "75"]]

And returns range of numbers like :

[64, 87, 75]	

Now I want to find the maximum of this range "numArr". Since I 
couldn't find a "max" function works on ranges I decided to sort 
them and take the first element.
But when I tried to sort like numArr.sort();

Error: template std.algorithm.sorting.sort cannot deduce function 
from argument types !()(MapResult!(unaryFun, 
FilterResult!(__lambda3, FilterResult!(__lambda2, char[][][])))).

Ok I said I will first copy the range to array then use sort. So 
I tried numArr.array

Error: no property 'array' for type 'MapResult!

Now only thing I can do with the range I have to call 
writeln();Why other functions of standart library are not working 
with this range type?