Adding value of two cells to get result in 3rd cell

[DocAElstein]

Did you realise and understand that your macro was incorrect? The issue was that you were using an incorrect macro. The macro was incorrect. Your formula was incorrect. The macro in your uploaded workbook was incorrect. So it did not work for me for that reason.
Your macro was using "E2" which was incorrect. You should have been using "E3"
In your uploded workbook, your data was in row 3 , so you must use B3 and E3. Your macro was using B3 and E2. That was the problem.