Protractor - Scroll down and click

I'm trying to simply scroll down in table and click on the element.

This is function which I have:

    var scrollIntoView = function () {
        arguments[0].scrollIntoView();
    }

    element.all(by.css('div.ui-grid-selection-row-header-buttons')).then(function(arr) { 
    var row = arr[8]; 
    browser.executeScript(scrollIntoView, row.getWebElement()).then(function () { 
    row.click(); 
    }); 
    });

This script actually work and even scroll down, bproblem start when i use higher number (index) in arr[];

For example 8 work, but if i use 20 it don't and I'm pretty sure there are like 50 values there so problem in that.

Any hint will help guys