It looks like a quoting problem. Either your context names are not in quotes, or you have not backslash-quoted your @ sign like this: '\@MAC'. The backslash is required because without it, Perl thinks you are trying to interpolate the value of a list named @MAC into your string. (I haven't used perl in years, so this is partly a guess).

All that said, the emacs-orgmode mailing list is discussing exporting org agenda views, which has the promise of reducing the need for external scripts like orghip.pl.