New Post: Excel sheet to array

Hello,
I'm trying to read the excel sheet and save all of its data into the 2D array. The problem is, that enything I do I get the error: System.NullReferenceException. I did FOR loops, I used foreach DataRow etc. but I still fail. My latest try:

            FileStream stream = File.Open(ExcelSourceFile, FileMode.Open, FileAccess.Read);
            IExcelDataReader excelReader = Path.GetExtension(ExcelSourceFile).ToLower() == ".xls" ? ExcelReaderFactory.CreateBinaryReader(stream) :ExcelReaderFactory.CreateOpenXmlReader(stream);
            DataSet ds = new DataSet();
            ds = excelReader.AsDataSet();
            DataRowCollection drc = ds.Tables[0].Rows;


int j=0;
            for (int i = 0; i < rows; i++)
            {
                foreach (DataColumn column in ds.Tables[0].Columns)
                {
                    DataFromExcel[i, j] = ds.Tables[0].Rows[i][j];
                    j++;
                }
            }

There might be some stuff from my previous tries. I know it must be the easiest thing to do with this library but I can't find the correct method. Hope someone can find few minutes to write it down.

Best regards,
Mike.