You don't have an end if, either put it all on one line
or
There are a few other issues as well, your definition of the range wouldn't work as you expect. you set C, D and E equal to the values of the range items as you have defined them as strings. You then assign the Range("C,D,E") which I think would just give you the entire columns. You can just do it as per the example below. I'm also not sure you want the brackets on the msgbox statement.
That said, I'm not sure this would really work as you are wanting. I don't think you would be able to edit the cells when the message box appears. I think you would need to end the macro each time to enable the user to change the cell. Also
Might be a slightly more efficient way of executing the loop.
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