[Solved] Strange function behavior

Hi,

I am reading a CSV file.

1587107584119.07397460937,109,0,443,5487,11174
1587107884119.04345703125,109,0,443,5503,11198
1587109990123.19384765625,165,0,445,5546,11242
1587110290123.16333007812,165,0,445,5567,11271

const storage = require("Storage");
var csvFile = storage.open("activepedom.data.json", "r");

Then I create an array from the entries.

function getArrayFromCSV(file, index) {
    i = 0;
    array = [];
    now = new Date();
    while ((nextLine = file.readLine())) { //as long as there is a next line
        if(nextLine) {
            dataSplitted = nextLine.split(','); //split line, 0= time, 1=stepsCounted, 2=active, 3=stepsTooShort, 4=stepsTooLong, 5=stepsOutsideTime
            diff = now - dataSplitted[0]; //calculate difference between now and stored time
            if (diff <= history) { //only entries from the last x ms
                array.push(dataSplitted[index]);
            }
        }
        i++;
    }
    return array;
}

To get an array with the first column from all lines in a certain timeframe (diff <= history):

times = getArrayFromCSV(csvFile, 0);

This works fine.
But as soon as I want to use the function for other columns, I only receive empty arrays ([]).
Example:

times = getArrayFromCSV(csvFile, 0);
steps = getArrayFromCSV(csvFile, 1);

times is filled correctly, steps is an empty array.
I can call each one individually, but never more than 1.
What is wrong?

Thanks