use strict;
use warnings;
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You should normally use strict & warnings in all scripts unless they're one-liners or if there's a good reason not to.

Use strict would show you that these two scalars are not being defined:

Global symbol "$caption" requires explicit package name at ./xml_p.pl 
+line 87.
Global symbol "$photo" requires explicit package name at ./xml_p.pl li
+ne 88.
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Update: wow! it's been stripped down! well done, much easier to debug for you!