So, does your module export the routine? You don't show us the relevant parts of your module, so it is hard for us to help you better. Maybe you want to use Exporter in your module?

package Upd::Common::System;
use strict;
use Exporter 'import'; # gives you Exporter's import() method directly
@EXPORT_OK = qw(getRemoteProcessIds);  # symbols to export on request
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... and in your main program:

use Upd::Common::System qw( getRemoteProcessIds );
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