Print with Sequential Numbering

I found a thread here:
http://www.excelforum.com/excel-general/590510-sequential-numbering-of-invoices-when-printing.html

...with a macro to print and have a number on the worksheet change sequentially each time the sheet is printed.

This is exactly what I need for the macro to do, but I can't seem to figure out how to get it to work for me. I need cell "S1" to start at 4000 and change by one each time it is printed.

The worksheet is currently being used as just a blank form that is hand written on.(I will build a userform to fill in and save as pdf at a later date)

I copied and edited the macro(originally written by royUK) and assigned it to a textbox on the right of the worksheet. See attached

Any help getting the macro to run successfully or help explaining what I did wrong is appreciated.

EDIT: currently using the print preview to save our trees until I can get the macro to run correctly

EDIT#2:
Here is the macro code that I was trying to use:

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Hello John,

Here is the updated macro.

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Ahhhhh, Thanks Leith!

...dang... I tried that and must have had something wrong, so I changed it back.

Works great....I just have to remember to subtract one number from the actual starting number...ie to start printing at 4000, enter 3999...no biggie, I can deal with that just fine.