Citing the documentation (emphasis mine):
$listbox->insert(index, ?element, element, ...?)

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Inserts zero or more new elements in the list just before the element given by index. If index is specified as end then the new elements are added to the end of the list. Returns an empty string.

You cannot use or die for functions returning always the empty string. See also the definition of $! in perlvar.

In reply to Re^5: Perl - TK - Listbox insertion problem by choroba
in thread Perl - TK - Listbox insertion problem by k0rn

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