Miért nem működik ez a kód? (C#, bináris keresés rekurzívan)

static bool BinarySearchRecursive(int[] sequence, int element, int first, int last)

{

if(last >= first)

{

int middle = (first + last) / 2;

if (sequence[middle] == element) { return true; }

if (sequence[middle] > element)

{

BinarySearchRecursive(sequence, element, first, middle - 1);

}

else

{

BinarySearchRecursive(sequence, element, middle + 1, last);

}

}

return false;

}

Hívása:

int[] array = new int[10] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

Console.WriteLine(BinarySearchRecursive(array, 3, 0, 9));

False-t dob.