unwanted message box

I am tring to make a code that will ask the user when the file is opened to enter there name, only if there is no user already entered for Responsiblity of the file

but after the code is run it asks me to "Put Your Code Here" with a message box & OK button

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Your code should be pasted into the "This Workbook" module. Is that where you have it?

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You don't specify a sheet to check, if the workbook has a different sheet active when it is opened then that cell on the activesheet will be checked

It doesn't mattere what you set the sheet to the critical line is not checking a specific sheet, or in this case it is even checking the newly opened file. You should run the check part before opening another file