Close button Excel 2003 greyed out can't be undone

Using Excel 2003, with below code it should be possible to turn off and on the close button of the Excel application.
Turning off (xapplicatieuit) works just fine; the button gets greyed out, but if I try to turn it on (xapplicatieaan) nothing happens.
Is this typical 2003 or am I doing something wrong?

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Anybody any ideas?

Last attempt. Anybody