#!/usr/bin/perl -w
use strict;

my $version = '0.8.34.0';

# This works as expected
$version =~ /(\d+\.\d+\.)(\d+)(\.\d+)/;
$version = $1 . ($2 + 1) . $3;  
print "$version\n";

# but this won't compile, --- why?
#$version =~ s/(\d+\.\d+\.)(\d+)(\.\d+)/{$1}$2+1{$3}/e;
print $version;