Leave no Empty Rows or Cells
When enter the data, it is important to ensure that it is entered correctly. Other than row 2 between the spreadsheet title and the column headings, do not leave any other blank rows when entering your data. Also, make sure that you don't leave any empty cells.
Data errors, caused by incorrect data entry, are the source of many problems related to data management. If the data is entered correctly in the beginning, the program is more likely to give you back the results you want.