|Where you put the code should not make any difference - except in the ThisWorkbook module. Don't put it there.|
You know that the code has to be run, right? Nothings happens automatically. There are many ways to run the code but the simplest is to click anywhere in the code so that you see the flashing cursor somewhere within the body of the macro. Then click the little green triangle above the word Run in the toolbar. Eventually you can attach it to a button in your workbook to make it easy to run.
I opened a new workbook and renamed 2 sheets, one to be "Data entry sheet" and one to be "Job YTD".
In C33 of "Data entry sheet" I entered 25.
I copied your code into a module and clicked the Run arrow.
I ended up with 25 in 'Job YTD'!C8 as expected.
I clicked the Run arrow 3 more times and ended up with 100 in 'Job YTD'!C8 since it added 25 to the value in C8 each time (4*25 = 100)
There's nothing wrong with your code, so you'll have to look elsewhere for the problem.
Click Here Before Posting Data or VBA Code ---> How To Post Data or Code.