|Subject:||Sub::Uplevel might be too old|
Have just tried to upgrade Data::ICal to 0.13. Unfortunately several tests kept failing. I tried with 0.12 and 0.11 and the result was the same. Looking closer the error was within Sub::Uplevel complaining about an undefined value. Just on the off chance I upgraded Sub::Uplevel (0.14) and tried to upgrade Data::ICal again and it worked perfectly. So you may want to add Sub::Uplevel as a prerequisite in your Makefile.PL with a specific version to ensure it gets a more recent version. Unfortunately I didn't check which version I had previously installed, but 0.14 seems to work without a problem.